Talk:Catch rate

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The computer science term for "Floor" is, in fact, "int(", which simply truncates the number. "round(" would make a value like 6.9 become 7; "int(" would make it 6. I believe Zhen is correct in this case. ~Evan

What was that in reference to? - Jshadias
Zhen's edit and your subsequent reversion, if I read the history right. ~Evan
He was just editing it to make it consistent with my other changes. In any case, the after revision is the right-side column. In any case, trunc() and floor() are the same, but int() is ambiguous. It simply means conversion to integer, which could be rounding or truncating. Wish I could get TeX-rendering working... - 刘 (劉) 振霖 09:40, 12 Feb 2005 (GMT)

Is this formula accurate?

When using the formula

Chance = floor (((( TotalHP * 4 ) - ( CurrentHP * 2 )) * CatchRate ) / TotalHP ) + Status + 1

with Pokémon with high catch rates (ex. Pidgey and Rattata), the formula says that there should be about a 200% chance to catch a Pidgey at 100% HP. But there isn't a 200% chance or even a 100% chance. I caught 5 Pokémon on Route 1 of FireRed without weakening any of them and I used 15 Pokéballs. Despite the sample size, the fact that the Pokémon escaped even once is enough to raise concern about the formula. Any other thoughts on the matter? -Wild Eep

Experimental data isn't the same as theoretical results. But then again, methinks you might be misinterpreting the results of using this formula. The formula does not return a percentage, it returns a number, and in order to capture a Pokémon, the randomly generated number between 0 and 255 (or possibly a higher number than that, say, 511) has to be below the number you obtain from this formula. But I'm not the game mechanics expert. - 振霖T 02:16, 25 November 2005 (CST)

Hmm. . . using the formula for any pokémon at any level with full HP and no status ailments with a catch rate of 255 gives an output of 511. Every site I could find has the exact same formula, and they all say the random number is between 0-255. Those that site sources site Meowth346 as their source, so maybe he knows, or can find out. Slim 15:54, 29 November 2005 (CST)

Indeed, there seems to be something off with either this formula or the listed CatchRates. Trying to catch a Pokemon simply by chucking a normal Pokeball at it (that is, no damage done, no status changes) simplifies as so:
Chance = floor (Poké Ball * (((( TotalHP * 4 ) - ( CurrentHP * 2 )) * CatchRate ) / TotalHP ) + Status + 1)
Chance = floor (1 * (((( TotalHP * 4 ) - ( TotalHP * 2 )) * CatchRate ) / TotalHP ) + 0 + 1)
Chance = floor ((( TotalHP * 2 * CatchRate ) / TotalHP ) + 1)
Chance = floor (( 2 * CatchRate ) + 1)
For any CatchRate of 128 or higher, Chance is at least 257. The random number between 0 and 255 this is compared to will always be less than this, and as a result any Pokemon with a CatchRate of 128 or higher should always be caught simply by chucking a Pokeball at it. Yet this does not seem to be the case -- you can't always catch an Abra this way, despite them having a CatchRate of 200. This should give them a Chance of 401, and thus a 100% catch rate. Wild Eep and Slim seem to have noticed the same thing. Opaopa13 05:12, 27 April 2007 (UTC)
I just noticed something -- note the following line in the article:
CurrentHP is either the wild Pokémon's current HP, or if its current HP is greater than 255, use floor ( CurrentHP / 4).
It doesn't make sense to simply replace CurrentHP with floor ( CurrentHP / 4) -- that would make for a very strange function, where a Pokemon with 256 HP would be easier to catch than one with 68. Replacing all of (CurrentHP * 2 ) just makes the problem worse. This suggests a typographical error somewhere in either the formula or its explanation.
I had a hunch, and replaced (( TotalHP * 4 ) - ( CurrentHP * 2 )) with (( TotalHP / 4 ) - ( CurrentHP / 2 )). Unfortunately, that's not right either -- according to that forumla, a Pokemon above 50% health will have a negative Chance value and thus can NEVER be caught. We know that is not the case. However, I suspect something along those lines is the solution. Perhaps one of those multiplications is supposed to be a division instead. Is there any healthy chunk of experimental data to look at? Opaopa13 05:24, 28 April 2007 (UTC)

The sensible thing to do is to ask someone who knows how to use a debugger/disassembler to investigate this. Unfortunately, the only person I know who can do this is pika. - 振霖T 06:57, 28 April 2007 (UTC)

Examining an emulated copy of Pokemon Red, I did, indeed, find it impossible to NOT catch any Rattata or Pidgey I threw a Pokeball at. I was more than ready to believe this formula were true. But, as Opaopa13 said, we know it isn't, because anyone who has played the Red or Blue versions knows Abra is not so easy to catch.

Interestingly, I tried the same thing on a Pidgey in an emulated copy of the Gold version (throwing a ball at it when it was at full health), and failed to capture it until my third try.


It would be easy to explain this if Abra's catch rate was just wrong, but the catch rates must have been data-mined, so that's out. Allow me to be completely speculative here, but perhaps it's something like a rare few Pokemon having an additional chance to escape capture? Or certain catch rates that are influenced by what badges you have? It would be odd to have something like that when the programmers could just alter something's catch rate instead, though...
Well, we _know_ we get the wrong results for Abra. I'm guessing there was some minor typo somewhere, or else some minor modifier to the formula we aren't aware of.
On a side-note, I'm still really confused by the "if CurrentHP > 256, use (CurrentHP / 4) instead" thing. I just can't imagine any reason, technical or modelling-wise, where "use CurrentHP = 255" doesn't work just as well or better. Or at least divide by 2! (Pokemon HP never exceeds 1024, right? Thinking in terms of the number of bits it takes to represent these numbers...). Opaopa13 19:22, 7 May 2007 (UTC)

I think, we should just remove the formula from the page until we can get some authoritative analysis, or otherwise from experimental data. - 振霖T 06:17, 8 May 2007 (UTC)

I strongly suspect that the only problem with the formula on the site is the 2. I know that's how the old equation simplifies, so the original was probably off as well. 1+INT(B*(2-P)*C+S) makes perfect sense. Then a Pidgey or other Pokemon with a catch rate of 255 is guaranteed to be caught, since at full health and no ailments, you get 256. Any number from 0-255 will be lower than that, so you'll always catch it. On the other hand, a legendary Pokemon with 1/10th of its health left, paralyzed, with an ultra ball thrown an it, is 1+INT(2*1.9*3+5), or 17. 17/256 (since it's a less than roll, not less than or equal to) is about 6.6% (1 in 15). That seems about right, given that it's taken an average of 15-20 ultra balls for me to catch most of the legendaries. The current formula says it would be 28/256, or 10.9% (about 1 in 9), which is definitely not right. Easiest way to test would be to repeatedly try catching something with a catch rate around 120, using a standard ball, and see if it happens about half the time. Arrkhal 03:50, 20 May 2007 (UTC)

The correct formula

Apparently someone at Smogon found an extremely complex formula on a Japanese website. A good friend of mine simplified it and it seems to be 100% Accurate:

( ( 1 - CurHP * 2 / ( MaxHP * 3 ) ) * Catch * Ball * Status ) / 256


  • 1 for Normal
  • 1.5 for Poisoned, Paralyzed, or Burned
  • 2 for Asleep or Frozen


  • A level 2 Rattata, with 13/13 HP, catch rate 255, using a Pokeball. No status effects.
    • ( ( 1 - 13 * 2 / ( 13 * 3 ) ) * 255 * 1 * 1 ) / 256
    • = 0.33203125
    • ~ 33%
  • A level 70 Regigigas, with 1/234 HP, frozen, catch rate 3, using a Dusk ball.
    • ( ( 1 - 1 * 2 / ( 234 * 3 ) ) * 3 * 4 * 2 ) / 256
    • = 0.093482906
    • ~ 9%

MK 05:51, 20 May 2007 (UTC)

This does appear to be more reasonable, however, I would like to see this so-called "extremely complex" formula. There may be some rounding going on which affects the precision of the results. - 振霖T 12:05, 22 May 2007 (UTC)
The original site had gone down, but thank god for Google cache. Here. It appears my friend was a bit exaggerating when he said complex; it's actually just a tad redundant. He reduced it to a simpler form is all. Cheers. MK 08:04, 1 June 2007 (UTC)
As I suspected, there is more to it. It seems that the formula result is interpreted in two different ways depending on what the value is. - 振霖T 12:25, 1 June 2007 (UTC)

Formula is nowhere near correct

I just tried catching a Lv. 13 Feebas at full health (30 HP). I threw three dusk balls at it (while in the cavern, of course), and they all broke. On the fourth try I was able to catch it. It has a catch rate of 255, so according to this formula I have maybe a 400% chance of catching it at full health. Even going by the catch rate alone, I should have had a 100% chance of catching it. This wasn't an atypical situation either. I tried catching a few more before and after this one, and I generally wasn't able to capture them until I weakened them (I caught maybe one or two without hurting it). Once I threw an ultra ball at one, and it immediately broke. I think the pokemon's HP ratio definitely has a lot more to do with catching it than what this formula suggests.

If there are any sources on that other function that someone submitted in here (I don't know how to reply to comments, sorry :<), then that would be really nice. But I tried that equation on the above-mentioned feebas and got (1-(30*2)/(30*3))*255*4*1)/256 (the pokeball page on here says that the dusk ball is 4x in caverns, and Wikipedia says it's twice as good as an ultraball, so I'm going with 4x), which equals 340/256, or 1.328125. This is still above a 100% catch rate on something that seemed like it was maybe 50%. Even going with the assumption that the dusk ball is only 3x better than a pokeball, I still got 255/256, which awfully close to 100%. So unless the dusk ball didn't have its 3x/4x effect (maybe from me fishing in the cavern instead of walking in the cavern?), I don't think this function is true either.

--Stele007 18:59, 21 May 2007 (UTC)

Were you surfing by any chance? There has to be some way to explain this. Feebas is extremely easy to capture regardless. My friend caught several using Quick balls (4x for the first 5 turns) immediately at the start of battle and none of them missed. If you were, perhaps the Dusk balls did not work because of surfing. I know they do work while fishing... MK 06:25, 22 May 2007 (UTC)
And by several I mean over a dozen. MK 06:28, 22 May 2007 (UTC)

Safari Zone

There's something I'd like to ask. In the Safari Zone, you can throw bait and mud in Generation IV. These are said to make Pokémon easier to catch. However, does anybody know of how EXACTLY do they change the catch rate (Or make them easier to catch somehow)? Thank you. - JMS 21:27, 22 December 2007 (UTC)

Actually, I think they alter the percent chance that the Pokémon'll run for it/accuracy of the ball. TTEchidnaGSDS! 22:53, 22 December 2007 (UTC)
Actually, the equation is posted on the Japanese wikipage for Capture Rate:
Solve for S (S = Safari)
S=(Capture Rate×100)÷1275×Rock Compensation÷Food Compensation
Rock Compensation = Times rock/mud is thrown at Pokémon × 2
Food Compensation = Times food is thrown at Pokémon × 2
Then solve for a, which is a special equation for this time around:
Just keep in mind that the more mud/rocks you throw, the easier it is to capture, but the easier it is to run away. The more food you throw, the harder it is to capture but it'll stay around longer. - GimmeTOKYO


The appearances of Pokémon such as Nosepass, Tropius, Carnivine, etc., would suggest that their catch rate is low. What the hell?!?!? Lord of Origami 18:44, 24 June 2008 (UTC)

Yeah... I don't know what that means, either. ~$aturn¥oshi THE VOICES 18:49, 24 June 2008 (UTC)
remove it because it makes no sense? i had thought dialga had a low catch rate when i got the game, and it turns out to be 30, quite high for a legendary... Lord of Origami 18:50, 24 June 2008 (UTC)
I know what it's saying: They look like the kind of Pokémon that would have a lower catch rate than they actually do. That's still based on the player's conjecture and probably not worth noting. --FabuVinny |Talk Page| 18:54, 24 June 2008 (UTC)

What I believe it was saying is that the rarity of these pokémon would suggest they have a low catch rate, just like one of a kind pokémon do. However, they actually have quite high catch rates. Does this seem right? Da Rammo 06:34, 22 April 2009 (UTC)

I put a note in the lede to try to address this last interpretation. AySz88 11:50, 24 December 2009 (UTC)

Easier explanation?

I think there should be an easier explanation included in this article, something of a tl;dr section. To me, this is all mathematical mumbo-jumbo, and I commonly fail anything and everything algebraic. I could honestly care less how the game determines how a pokemon is caught, I just know that I need to lower the HP of the wild Pokémon and possibly inflict a status problem on it to catch it. Also, on major thing that's missing from the article is it doesn't explain if a higher number for a catch rate is better or worse. It may be a dumb question to ask (but I don't honestly get it, either) but you quite often have to write for the five-year-old poké-tards that will be here.

Higher number for catch rate increases likelihood of capture. It's why Mewtwo's is 3. TTEchidna 04:39, 28 June 2008 (UTC)

My brain hurts... too much math... Diachronos 16:55, 1 October 2008 (UTC)

Will you please make this article in a way that actually makes sense? It tells me nothing helpful. Alakazam 2

I agree, a simplified, even if less informative, version of this article would probably be more helpful to a lot more users.Gastly's mama 15:36, 7 December 2008 (UTC)
I tried to write a more accessible way to interpret the formula. Also see Reworking the a term below.... AySz88 11:51, 24 December 2009 (UTC)

CatchRate Calculator

I have written a small catch-rate calculator program. You put in details of the opponent's HP,Max HP, Base CatchRate,status ailment, and choose which ball you are using (along with ball-specific factors), and it tells you the chances of catching the pokemon. Should i include a link on the page? Lord of Origami 12:06, 10 January 2009 (UTC)

I think so. Where does all this come from anyways? O_O --Sivart345 01:58, 27 March 2009 (UTC)

Heavy Ball

How does it work into the formula if the ball bonus adds instead of multiplying? Does it add before or after the status bonus? --Kaoz 16:29, 28 September 2009 (UTC)

Order of operations. Multiplication first. ht14 16:42, 28 September 2009 (UTC)
Are you sure? Because if it works just like I think you're saying, you just replace the Ball Multiplier with a flat "+30" rate (or whatever technically applies). I calculated the catch rate of Groudon using a Heavy Ball VS a Great Ball, and the Great Ball outperformed the specialty Poké Ball. If that's the case, Heavy Balls are pretty useless.--Purimpopoie 13:33, 18 October 2009 (UTC)
I doubt that "order of operations" applies here; it's relatively easy to just apply the +30 before the multiplications coding-wise (much like using parenthesis). One would need to look at the game code somehow, probably, to see for certain. AySz88 12:07, 24 December 2009 (UTC)

Luxury or Friendly?

Which is more effective? ht14 01:05, 29 September 2009 (UTC)

it depends, i know squat about the catch rate, but i do know the luxury ball increases how fast the pokemon's friendship raises while the friendly(?) ball gives an immediate boost... by how much i'm not quite sure. - Geomexis 12:59, 18 January 2010 (UTC)
Luxury Balls increase the rate at which your pokemon becomes friendly from actions as outlined in the Happiness article. Friend Balls automatically set the pokemon's happiness to 200 (instead of the usual 70) when caught. Both poke balls have a catch rate of 1x. Max happiness is 255 and happiness-based evolutions happen at 220+ so usually the Friend Ball will get you there quickly for cheap. ~mjblink- unsigned comment from mjblink (talkcontribs)

Reworking the a term

In every location in this article that I can tell, it would be clearer if a were already divided by 255, i.e. substituting a/255 = a/(2^8 - 1) in each formula with a new variable. (Even that odd-looking 16711680 is 255 * 65536 .) Then a simply becomes equal to the approximation to p and there is an obvious intuitive meaning to it. I used this idea in the new lede, and it'd probably be clearer to do this in the rest of the article as well.

Is there some reason why a was defined this way that I don't know of? AySz88 11:39, 24 December 2009 (UTC)

Trivia on HP

There's a bit in the "Trivia" section about high-HP Pokémon being easier to catch at 1 HP than lower-HP ones. This is true, but it also states that "Pokémon with higher HP stats (such as Chansey) are easier to capture when their HP is reduced, despite low catch rates compared to others." But there isn't a big-enough effect to overwhelm the catch rate except at very very low HP levels. The equation in the current article can be reorganized this way:

a = catch_rate * ball_bonus * status_bonus * (1 - 2/3 * (currentHP / maxHP) )

And at 1 HP:

a = catch_rate * ball_bonus * status_bonus * (1 - 2/(3 * maxHP))

And comparing the HP penalties at 1 HP:

  • 10 HP max: 1 - 2/(3 * 10) = 1 - 2/30 = 6.7% penalty (i.e. 0.933x)
  • 20 HP max: 1 - 2/(3 * 20) = 1 - 2/60 = 3.3% penalty
  • 100HP max: 1 - 2/(3 * 100) = 1 - 2/300 = 0.66% penalty
  • 200HP max: 1 - 2/(3 * 200) = 1 - 2/600 = 0.33% penalty

... Once you get past 20ish HP, shaving off bits of that last 3% of (multiplicative) penalty is pretty negligible, equivalent to around 7 points of catch rate at most (3% of 255). AySz88 10:40, 25 December 2009 (UTC)

Generation I?

In Generation I, the mechanisms are somewhat different. For example, the number of shakes doesn't seem to be determined randomly and a Poké Ball can even entirely miss a target. Do the Gen. I games also use a completely different formula or does it work the same way as currently described in the article? - unsigned comment from Socob (talkcontribs)

The formula is definitely different in Generation I - I think Pokémon with very high catch rate (like Pidgey) were more difficult to catch, and Pokémon with very low catch rate (like Articuno) were easier to catch. By the way, the number of shakes has not been determined randomly since at least the beginning of Generation IV. Ultraflame 16:06, 16 May 2010 (UTC)
I thought so. It would be nice if we had some information about this, but I don't think that's very easy to get. About the shaking - I'm not sure if that's also what you meant, but what I was referring to by "not randomly" in Generation I is that a Ball will always shake the same amount of times on a Pokémon as long as you don't change its HP/status condition (unless it's caught). -- Socob ( Talk | Contribs ) 10:22, 21 May 2010 (UTC)
Actually, I just thought of this: You can try asking Pokémon ROM hacking communities about Generation I catch rate mechanics. The PokéCommunity is one of the few Pokémon sites that has a dedicated sub-forum for ROM hacking discussion. Ultraflame 19:32, 21 May 2010 (UTC)
I have put up a complete analysis of the R/B/Y capture algorithm on my website, based on the actual code. Something about it should at least probably be included on the page. Dragonfree 09:00, 25 February 2011 (UTC)


Somewhere else on this site, I read that the lowest possible catch rate is 3 since if it were any lower, the Master ball would have a chance of failing. KurosakisTwin 17:22, 5 August 2010 (UTC)

False. The Master Ball bypasses the formula entirely, so even if the catch rate were 0, the it would still catch the Pokémon. --a_magical_me 23:09, 5 August 2010 (UTC)
How do you know that? As far as I know, the Master Ball simply uses a value of 255 for the 'BonusBall' variable in the formula.
With this, if all the other factors in the formula multiplied would result in a number less than one, 'a' would be less than 255 and thus, the Pokémon would have a chance of escaping. Quoting from the article, "The minimum value for 'a' (for a Pokémon with full health) would be ⅓ × catch rate." Since the result of the formula without the BonusBall component has to be at least one for the Master Ball to work reliably, this means that the catch rate must at least be 3 (as ⅓ × 3 = 1).
This seems to be reasonable evidence to me as to why we've never seen catch rates lower than 3. -- Socob ( Talk | Contribs ) 12:29, 7 August 2010 (UTC)
Also, I'm pretty sure that the game wouldn't make an exception for the master ball. That would result in a lot more code, and therefore it's just easier to not make more code and make the lowest catch rate 3 so that the Master Ball can catch anything. KurosakisTwin 09:01, 11 August 2010 (UTC)
Socob, I know because it's what UPC says and it's what the reference in the article says. Also because I have read the relevant code in both Diamond and HeartGold, and I can tell you that the Master Ball is simply not implemented in the way you suggest.
KurosakisTwin, it does not require "a lot more code", just a couple lines—a small if statement—and is what any sane programmer would do.
And here is something to think about: the lowest catch rate has been 3 since the beginning, way back in Red and Blue, when a completely different algorithm was used. --a_magical_me 07:33, 21 August 2010 (UTC)
Even UPC and the reference have their sources (which might be false), and even if they aren't, no matter how it's actually calculated in the games' codes, the Master Ball works without fail, so the statements on UPC don't necessarily indicate the actual calculations.
Still, if you have viewed the code as you say, there's not much I can argue against that. All of what I've said above was, of course, simply evidence that pointed in the direction of a Master Ball with a value of 255. Naturally, the catch rates of 3 might be there to prevent "a" from being below 1 for entirely different reasons. If "a" is actually rounded down to an integer (which is actually stated in the article), then it would have to be at least 1 for the formula to work. However, this seems strange considering your last statement about the algorithm in Generation I. I haven't looked at it closely, but I guess it also needed catch rates of at least 3. I wonder, though, why the developers would go through the trouble of changing the algorithm, but leaving in the necessity of those catch rates of three or higher.
Long story short: You looked at the code, I didn't, so you're probably right. -- Socob ( Talk | Contribs ) 15:28, 24 August 2010 (UTC)

Critical Capture

Should we write about critical capture, of black and white, here?--Kantenoh 21:56, 18 December 2010 (UTC)

I belive from what i've read and when it happened to me,that there's a not so small chance (I don't know how high), that the pokeball will, when thrown, let out a woosh (a higher pitched on than normaly), absorb a pokemon, let out a metalic sound (ping a little like its captured), shake(a fast shake not a roll) in mid-air, fall down like usualy, then shake only once (not 3 times like usually), and have because of that idk probably about 3 times the capture ratio i suppose. Codebracker

Trainer pokemon level

I've been thinking about it for quite some time now, but pokemon are easier to capture depending on the level of the pokemon you battle it with.

I tried to catch a pokemon with a lv.5 and lv.8 pokemon and i couldn't catch it with ultraballs in 5 tries, than i swaped it for lv.75 pokemon and it worked on first try.

So could the level of the trainer's pokemon also apply somewhere in the formula? Codebracker

5 tries is not NEARLY enough trials to draw any kind of conclusion from. If you really want to test this, you're going to have to set up a comprehensive experiment and run it thousands of times. Alternatively, someone who has read the source code can tell you for sure. --Toksyuryel 04:40, 9 January 2011 (UTC)
I haven't read the code, but the people who wrote this article have. The only time your Pokémon's level is factored in is when you are using a Level Ball. This was actually recently brought up on the forums. --SnorlaxMonster 04:41, 9 January 2011 (UTC)

Critical Capture Rate

What is the rate of a Critical Capture in Generation V? --Nathan2055talk 21:22, 27 February 2011 (UTC) That's what I want to know in Gen 6.--Hydreigonfan1 (talk) 14:02, 19 December 2013 (UTC)

High or low?

It should say in the very beginning whether a high or low number makes it easier/harder for a Pokémon to catch. I don't even think it's ever in the article. - Colorshade 22:20, 13 April 2011 (UTC)

Good suggestion; I've added that. :) AySz88 17:29, 18 May 2011 (UTC)

Critical capture ambiguity

In the Critical Capture section right now, it says "A random number is generated, and if it is less than the modified value, a critical capture occurs." But what range is the random number in? AySz88 20:38, 18 May 2011 (UTC)

It seems sensible for the range to be 0 to 255 inclusive, since that is the base of the modified value. Naokohiro 23:54, 7 May 2012 (UTC)

Catch chance

Can anybody tell me whether the chance to catch a Pokémon in Generation I is equal to them in Generation II (and the others) or the chance is different? E.g. I throw an ordinary ball to a full-healthy Weedle. Is the chance to catch it in all generations identically (according to Weedle 33,3%) despite the fact the capture methods are different? I'm sorry again for my bad English! --LaBumm 04:29, 24 September 2011 (UTC)

Doubt Generation III Algorithm

I'm starting to doubt the generation III algorithm. These are my findings in FireRed. I calculated for a paralyzed lvl 50 Moltres at 1 HP (exactly 1 HP due to endure) with a maximum HPmax of 165 (courtesy of and a capture rate of 3 with an Ultra Ball.
A = (3x165-2x1)x3x2/3/156x1.5 = 8 (rounded down)
B = (2^16-1)xA^(1/4)/(255)^(1/4) = 27581 (rounded down)
This gives a success rate of:
(27581 / 65535)^4 = 0.031 (rounded down) or 3.1%
At the moment I have thrown 400 (FOUR HUNDRED!) Ultra Balls, and still not captured it.
The chance of that happening would be (1-0.031)^400 = 0.000002902 or 1:344550
Please tell me I made a mistake in my calculation. It lies rather far outside the normal 0.05 error margin for experimental testing of hypotheses.
I redid the same sort of testing for Zapdos, I didn't calculate my exact chances, this time I didn't manage to catch it in 200 tries.
Ghostbird 00:11, 25 November 2011 (UTC) EDITED: Ghostbird 12:41, 28 November 2011 (UTC)

I retried catching Moltres and this time I caught it after 15-20 tries. (I wasn't counting)
The only differences I knew of:

  • I had defeated team rocket in Saffron and Giovanni in Viridian's gym.
  • I was facing it with a pokémon over lvl 50. (However I caught Articuno using a lvl 30-ish pokemon)
  • It was at more than 1 HP (he had a two pixel health bar).

I retried catching Zapdos and this time I did 200 fruitless tries. I noticed that though it had very little health left, it almost always broke free at the first check.
Something that you should know:

  • I've been using a state reload system to quickly retry catching when the capture failed. (Otherwise these capture tests, which require as much attempts as possible, are infeasible.)

I managed to Capture Zapdos on try 41 after reloading the original save (not a state save), (re)initiating combat and then using the reload state method. This time it generally broke free much later, often passing two shake checks and only breaking free at the last check, until I captured it.


  • There's something that influences catch rate, which kicks in before you are at the [Use|Cancel] screen after selecting the capture device (Ultra Ball).

Ghostbird 17:55, 28 November 2011 (UTC)

  • I believe your problem is the fact that you are using the same save state over and over. Typically, random number generators (RNG) initialize with a single random number called the seed and derive subsequent random values using a mathematical formula. When you save a state on your emulator, you are also saving the current state of the RNG used. So theoretically, you are asking the RNG for a random number in the same exact state each time, resulting in the same result every time you reload. I think this is why you managed to capture your Zapados some time after reloading the original save (new random seed). I'm not sure exactly how you used the reload state method after reinitializing combat. Did you have to hard reload the game 41 times or did you reload once and use the save state 41 times? Please elaborate on this. Invgamma 20:45, 23 December 2011 (UTC)

Investigation of the RNG

I recently thought about the specific cases where the catch formula does not seem to describe the behavior of certain Pokemon. On review, I noticed that the catch formula assumes that every random number generated is completely independent of every other random number. If the random number were using some sort of non-deterministic input to calculate a new seed every time a number is requested, this certainly would be true; however, this is normally not the case.

Consider the case of an encounter with a rare Pokemon with a somewhat high catch rate. Assume that the game finds a new random seed whenever an encounter is supposed to happen (probably sometime before) and uses that number to both determine the Pokemon encountered and to seed further random numbers. When you ask the RNG to generate the next couple random numbers, they are completely dependent on the algorithm used and the seed. With a rare Pokemon, the number of random seeded values that result in an encounter with it is sizable, but smaller than a common Pokemon. If the RNG is not reseeded, the number of possible scenarios (with strings of random numbers) greatly decreases. In this case, it could simply be a mathematical oddity (of the algorithm) where the select few seeds that allows an encounter with a rare Pokemon has subsequent random values that allow it to easily be caught (or even possibly more difficult to catch).

If this is the case, then the rarity of each Pokemon can easily influence catch probabilities by "shaping" the subsequent numbers (by pure mathematical accident). Some random values might even be impossible for, let's say, the first pokeball thrown right after an encounter of a rarer Pokemon. Invgamma 21:02, 23 December 2011 (UTC)

  • Just ran a couple of scenarios on an emulated version of Pokemon White. If I load save states right before encountering a Pokemon (a legendary that you can approach), you can get different random seeds for the battle (first action resulted differently each time). This probably means that the seed for the battle is determined based on conditions right when you encounter the pokemon. Invgamma 23:58, 23 December 2011 (UTC)
Just to let you know, I've done the investigation already :) Check Smogon's RNG Research thread[1] to get filled in on how the game seeds the battle RNG and (approximately) does the majority of battle RNG operations. RNG is only reseeded between battles. Every game uses 4 random numbers for the shake calculations, the only thing new in gen 5 is the critical capture calc.
First it calculates if critical capture, then the shake/capture values. If result < CV, pass check. Total of 4 for regular catch, 1 for CC.
Come ask about the battle RNG in IRC, synirc #smogonwifi

A comment on Critical Capture

Having read through the article and especially the section describing the critical capture, it occurred to me that since it usually uses three shake checks, it is cubing the base probability of capture. By only using one shake check, it does not get cubed, which is why it allows capture to occur easier. However, the amount it increases capture rate is dependent on how difficult it is to capture in the first place. Another way to think about what I previously said is to take any specific set of conditions (a species in the wild, how much HP it has out of its total HP, and if it has any status ailments) and calculate the probability of catching it with any one type of ball. You could then take that final probability and, assuming that the same exact conditions and ball are used, a critical capture will increase the chances of capture to the cube root of the capture probability without a critical capture. This relationship means that the lower the capture rate is in specific conditions, the more difference a critical will make in the probability of catching it.

A couple examples would be if a legendary pokemon is attempting to be caught in specific conditions that would create a normal capture probability of 1%, if it is instead a critical capture, that will increase to a 21.5% capture probability. However, at higher capture probability this difference is much smaller. If there is an easily captured pokemon at low health, with a status ailment, and the normal capture probability is 90%, a critical capture in the same circumstances would mean a 96.5% capture probability.

Is this worth adding into the article, or am I just having too much fun with the math?Mor'ranr 16:07, 19 January 2012 (UTC)

It would be cool to see the adjusted probability of that helping, but I don't think it would be one dimensional because of the different critical capture rates.
If critical capture calc passes, shake check once; else thrice.
Kaphotics 00:04, 2 February 2012 (UTC)
I definitely think it is useful to point out the relationship, and the difference in effect between Pokémon with low rates and high rates. But it might be better to use "realistic" numbers for any examples in the article (i.e. 3/255 instead of 1%). AySz88 05:07, 24 February 2012 (UTC)
Wait, shouldn't it be fourth root? The article says there's needs to be one shake check to pass instead of four normally. AySz88 05:14, 24 February 2012 (UTC)
Oops, no, was accidentally looking at a different generation. AySz88 07:40, 25 February 2012 (UTC)
Fourth roots and third roots never happen in game. The b equation listed is just a probability of you catching (ie all the shake compares lumped together). It does a*0x100 > rand(0,65535) for a pass shake calc. 4 times for gen 3-4, 3x for gen 5 after criticalcapture. That's the one gripe I have about this page, the mathematical approximations aren't what the game does. Kaphotics 19:22, 25 February 2012 (UTC)
I'm not sure what you're saying here. Yes, the algorithm used for a shake check is not literally a third or fourth root. But while it's nice to document the exact algorithm somewhere, it's probably much more useful to explain the practical results of the algorithm - thus why there are the approximations used in the lede (and occasionally sprinkled elsewhere). You can be sure that when the game designers were playing with formulas, they were doing it in general terms, not caring about whether the RNG was 16-bit or whether a division rounded up or down. The algorithms in the code are crafted to follow their intent. (The difference is famously illustrated in that old "Pokémon: Serious Business" image that had an old version of this article - indeed, it's what inspired me to craft the new lede in the first place.) Let's keep our audience in mind.
Though, that does bring up something else: it might be a good idea to more clearly separate the exact algorithms from the approximate interpretations, instead of the hodgepodge mix in the article currently. AySz88 05:23, 26 February 2012 (UTC)
Kaphotics (or, anyone), could you elaborate on "It does a*0x100 > rand(0,65535) for a pass shake calc."? I don't understand how multiplying by 256 is equivalent to 65536 / (255/a)(1/4) as listed in the article. —Naokohiro 10:55, 8 May 2012 (UTC)
When I wrote that I wasn't thinking clearly, it does keep the 4th root and such. For every check it does - rand(0xFFFF) and compares it to b. If it is less than b, it passes the wiggle calc and checks again until it either fails or the wiggles result in capture. Kaphotics 17:45, 22 May 2012 (UTC)

Generation V -- Interesting Probabilities

Since we are still getting the 4th root of the initial probability a and doing 3 shake checks, that makes the chance of capture when the critical capture chance is 0 equal to a3/4.

This takes what would normally be a linear probability always equal to a and puts it on an exponential curve.

If we have more than 30 in the dex, the probability now changes. There is a (a*m)*a1/4 chance of getting a critical capture and then succeeding in capture. Let m be the multiplier for critical capture which is based on the amount caught in the Pokédex. There's also a (1 - a*m)*a3/4 chance of getting a normal capture. So, the total chance of getting a capture is now (a*m)*a1/4 + (1 - a*m)*a3/4 (with m=0, 0.5, 1, 1.5, 2, or 2.5 respectively).

What this does is make an increasingly steeper curve the higher the value of m, but the curve always starts at (0, 0) and ends at (1, 1). Actually, in the higher values for m, the curve actually gets so steep that it begins to increase a by more than 100% for part of the curve, which suggests a higher chance of capture when the Pokémon isn't completely at its weakest. I just thought this information was interesting. It's almost like catching Pokémon has its own level up system. Naokohiro 00:55, 8 May 2012 (UTC)

Is this something worth mentioning in the article? —Naokohiro 00:58, 8 May 2012 (UTC)
I haven't had Critical Capture debugged, but I noticed that what is currently the going theory on the page wasn't matching up with the battle RNG. The critical capture section is really... empty, so why not? If you want to put it in the article be sure to have an image of it! Kaphotics 17:45, 22 May 2012 (UTC)

Gen V Shake Rate

Isn't the Gen V shake rate listed functionally the same as the Gen IV one? It seems slightly redundant having both formulas up, claiming to be different...Unknowen900 (talk) 08:33, 23 July 2012 (UTC)

Level ball

The formula seems to be flawed for the Level Ball. I'm playing HeartGold and I was trying to catch a level 4 Aipom (full health) using my level 58 Crobat. According the the formula, I should have had a 140% chance of catch the Aipom with a Level Ball. I threw 3 or 4 level balls at the Aipom and all of them broke. I've generally found most Pokémon to be more difficult to catch than this formula and their catch rates indicated that they should be, but the Level Ball, in particular, doesn't seem to increase catch rates significantly, if at all. RS89 (talk) 01:59, 27 November 2012 (UTC)

The number is 140, Then it generates a random number from 0-255, and it does something else. It's not a percentage. I think. --Abcboy (talk) 02:21, 27 November 2012 (UTC)
Nevermind. I just realized I missed a step. RS89 (talk) 02:39, 27 November 2012 (UTC)

The Formula Simplified (as much as possible)

Here's the simple explanation (in Gen V): Your chances to catch a Pokemon are based on 5 things normally (6, if you count capture power, but that is not a normal thing).

1st. Species Specific Catch Chance: Meaning some pokemon are super easy to catch and come are super hard. The only way to look get this is to just look up the Pokemon, it's Catch Rate is listed in it's info box (on a scale of 0 to 255). So, if it has a 255, you will catch it.

Pretty much a 100% chance. If it is a 45 (like Celibi) then you only have a 6% chance to catch it before any other factors.

2nd. It's Current Health: If the creature is at full HP, than your normal chances are cut to 1/3. This means that a 255 would be a 33% chance with a Pokeball at full HP and a Celibi would be a 2% chance. This continues to decrease all the way to 1 HP,

which gives you between 99% and 99.9% of your normal. Meaning the HP basically no longer negatively affects your catch chance at 1 HP.

3rd. The Type of Ball Used: You have a normal chance with a Pokeball. Your chance is multiplied by 1.5x for a Great Ball, 2x for an Ultra Ball, 3x for a Repeat or Net Ball, 3.5x for Dive or Dusk Ball, 4x for a Timer or Nest Ball (at max), and 5x for a Quick Ball.

These all assume you are using them correctly (i.e. Dusk in caves, Repeat on owned Pokemon, and Quick in round 1). Timer and Nest balls can multiply your chances by everything from 1x to 4x (including 3.2134x or some other random number).
Nest Balls are 4x for a level 1 Pokemon, 3x for a level 11, 2x for a level 21, and 1x for everything above level 30. Timer balls are 1x in the first round, 2x after 10 rounds, 3x after 20, and 4x after 30 rounds.
This means, if you are trying to catch a pokemon with a catch rate of 255 (easiest possible) at full HP with a Great Ball your chances would start at 100% for the 255, drop to 33% because he is at full HP, and then would increase back to 50% with a Great Ball ((((255 * .33) * 1.5) = 114.75) 114.75/255 = 0.495).
The same Pokemon would be a 100% chance of catching it with a Quick, Dive, or Dusk Ball (also 100% with a Nest or Timer Ball at max conditions). It is still a 99% chance with a Repeat or Net Ball. It is only a 66% chance; however, with an Ultra Ball or a 50% chance with a Great Ball.
It would be a 33% chance with a normal Pokeball (Basically normal, Great, and Ultra Balls suck).

4th. Status Ailments: This is simple, and it stacks multiplicity. Meaning if the pokemon is Paralyzed, Poisoned, or Burned then your chances are 1.5x and if it is Slept or Frozen, then your chances are 2.5x.

So, in the above example, a 255 Pokemon (100%) at full HP (33%) using a Great Ball (1.5x) gives you a 50% chance. If that same Pokemon is Paralyzed then your chances increase to 75%. If it is Paralyzed AND Poisoned then your chances are 100%.
Also, if it was JUST Asleep (no Poison or Paralysis) then your chances are still 100% ((255 (Catch Rate) * 0.33 (Full HP) = 84.15) (84.15 * 1.5 (Great Ball) = 126.225) (126.225 * 2.5 = 315.5625) That is higher than 255 so you have a 100% chance).

5th. Dark Grass: Basically this means that if your encounter is in Dark Grass it is harder to catch the Pokemon based on how far through the game you are. In the beginning of the game, it will further decrease the penalty for it's HP by up to half and at the end of the game you will have full chances.

100% normal chance if you have more than 600 Completed Pokedex Entries (not just seen, but caught). You will have a 90% of your normal chance if you have between 451 and 600 completed Pokedex entries, 80% for 301 to 450 entries, 70% for 151 to 300 entries, 60% for 30 to 151 entries,
and 50% of your normal chance if you have less than 30 completed Pokedex entries. Meaning, almost the entire game you will sit at 60% in dark grass. This means that if you have a Pokemon with a Catch Rate of 255 at full HP and you tried to catch him with a normal Pokeball then normally you have a 33% chance.
If it happens in Dark Grass you have a 16.6% chance. If you used an Ultra Ball, normally you would have a 66% chance, in Dark Grass you would have a 33% chance. The math is a little longer to show here but ...
Here: (250HP x3 = 750 - (250x2) = 250) <- 1st half of the HP formula. now ((250 * .5 (Dark Grass)) = 125), then (125 * 2 (Ultra Ball) = 250) and Finally ((250/(250 * 3)) = 0.333) <- 2nd half of the HP formula.

I know that is sort of long, but I hope that makes more sense. Degrelecence (talk) 06:18, 17 June 2013 (UTC)

EDIT: Sorry forgot that whole Capture Power thing. The 6th factor is Capture Power. The catch rate is multiplied by 1.1x if Capture Power ↑ is active, 1.2x if ↑↑ is active, or 1.3x if ↑↑↑, Capture Power S, or Capture Power MAX is active. Degrelecence (talk) 06:34, 17 June 2013 (UTC)

You said that for <30 and 30-151 the percent chances are capture in dark grass are 50% and 60% respectively, but the table provided in the article says these values are 30% and 50% at these intervals. Which one is correct? --Skit7548 (talk) 05:28, 28 October 2013 (UTC)

Generation V shake checks

The article currently states that three shake checks occur for a regular capture in the Generation V games. This is contradicted by Kaphotics on Smogon (and earlier on this page), who claims that four shake checks occur. Which is correct? Arcorann (talk) 08:31, 17 June 2013 (UTC)

Critical Capture chances?

How rare is it to get a Critical Capture? I'm really confused with this. We could put this on the Critical Capture section. I know the more you capture Pokemon in your Pokedex the more chance you'll catch a Pokemon and it usually always works without fail except if you don't catch Pokemon a lot. But I want to know how rare it is. I got 3 Critical Captures in 1 Day and 2 of them were one after another. How rare is it so we can put it on the Critical Capture area?--Hydreigonfan1 (talk) 14:00, 19 December 2013 (UTC)

It says how rare it is. To be simple: whatever number the final catch rate is, that number is multiplied by 0, 0.5, 1, 1.5, 2 or 2.5 (depending on how many Pokémon you caught), and then a random number is generated. If it's lower than the number received by multiplying final catch rate, critical capture occurs. Uploader (talk) 14:12, 19 December 2013 (UTC) PS. The only thing missing is what's the interval for that random number. The critical catch success otherwise is based on how likely you are to catch mon (and isn't a guaranteed catch unless you would catch it anyway). Uploader (talk) 14:14, 19 December 2013 (UTC)

Generation II Shake Probability table

Why isn't this an actual table? --Det (talk) 08:36, 13 January 2014 (UTC)

It is, actually. It just doesn't have any pretty borders. ...Also, it's arguably formatted badly (text alignment).
I did something to it. I experimented with the styles that are on other tables on the page, but it didn't look good to me, so I kept it dead simple. Tiddlywinks (talk) 09:27, 13 January 2014 (UTC)

Critical Catch

The example can't be right. It says, that catching Kyurem with catch rate 3 with max HP and Pokéball has a probability of 0.4%, which is right. For a critical capture the value 25.03% is given, which is (0.4%)^(1/4) or the forth-root of the chance, respectively. But why should it be the forth-root instead of third-root? Remember that in Gen V only THREE shake checks are performed. The example would be right for Gen IV, but not for Kyurem. Or is there something I do not understand? - Pokémon Questions? -- 23:37, 18 January 2014 (UTC)

I have checked the version history now. In fact this example has been done before finding out that since Generation V only three shakes are performed (or one for a critical capture). It must be a wrong example. Otherwise I has no mathmatical sense. It's almost like saying 1/3 * 4 = 1. You cannot have only three shakes, but set a single shake to the extend of 4 to get the whole capture chance p. The real chance of this example has to be 15.77%.- Pokémon Questions? -- 00:36, 19 January 2014 (UTC)

The nearest 1/4096

"and then rounded to the nearest multiple of 1/4096"

I always read this, but... what does it mean?!? The first multiple is 4096 to get a whole number, so if I have numbers between 0 and 255 I always would round them to 1. Nonsence. I just don't understand this expression. - Pokémon Questions? -- 03:34, 19 January 2014 (UTC)

I believe it means the game uses 12 fractional bits. If the program is executed in the order shown, "(3*HP_MAX - 2*HP_Current)*rate*ball/3/HP_MAX*status", the "/3" will round the result then "/HP_Max" will round the result again. If we were only dealing with int data types, each division would round the result to the next lowest integer (1/3 = 0, 13/10 = 1, 9000/4096 = 2). The fractional bits ensure a calculation like 400/3 yields 546133/4096 (133.33325) instead of just 133 - an error of .006% instead .25%. Is it going to make much of a difference after you round to the nearest whole number? Not really. But when you have the memory and the processing power, this becomes a trivial process, so why not. Rulingsword (talk) 04:47, 21 January 2014 (UTC)

Generation VI Catch Rate Formula

I think that we can say with certainty that the catch rate formula has changed drastically in Generation VI. Zygarde has a catch rate of 0 which would mean that it could not be captured except with a Master Ball. This is assuming that the catch rate given is correct. - unsigned comment from Mudmaster97 (talkcontribs)

Most Gen VI Pokémon's catch rate aren't known, so it says 0. Glik (talk) 15:54, 12 February 2014 (UTC)

Blowing into the microphone

In generation IV it was rumored that blowing into the microphone increased your chances of catching the Pokémon. I know to take rumors with a pinch of salt, but it appeared as an official tip in the Official Nintendo Magazine a few years ago. --evacino (talk) 19:51, 19 February 2014 (GMT)

This page confuses people horribly

After browsing through a bunch of catch rate-related questions on PokémonDB, I have come to the conclusion that this page is frightfully confusing for the average fan. People scroll down to the later generations, see the single big formula graphic for the modified catch rate in generations III-IV, plug in the numbers, get something that looks vaguely like it could be a percentage and then assume that's it. This could probably be avoided or mitigated by rewriting or at least rearranging the page so that the shake probability calculation is at least closer to the modified catch rate, so people see that there is more to it than that one formula, but I'm open to suggestions. Any thoughts?- unsigned comment from Dragonfree (talkcontribs)

Gen V Shake-Break Comment

In BW2 the 1 shake-brake comment is exactly like it is execpt with "Aww" not "Aww" also the 2 shake-break comment isnt listed but I will find out what it is ( sry I havent been signing my comments I keep forgetting) Pokemonisawesome2 (talk) 02:42, 19 July 2014 (UTC)

The 2 shake comment is not listed, because it doesn't exist. In Generation V, a Poké Ball will never shake two times. While speaking of this; since the game performs 3 checks instead of four, doesn't that make Pokémon more likely to be caught? Eridanus (talk) 10:13, 23 August 2014 (UTC)
thats exactly what i was getting at I have caught nearly every pokemon in white 2 and have never seen it shake twice however I am not sure that this means it only checks 3 time perhaps it checks twice before one of the other shakes? (Like it mabey theres a hidden check that it dosent show?) But if it is just the fact that it only shakes 3 time that would sigfigantly lower the catch rates Pokemonisawesome2 (talk) 16:27, 24 August 2014 (UTC)
Likely there are only 3 checks for some reason, since it's Generation V, and probably people have simply ripped out code from theame itself. Also, I am sure 3 checks would actually make Pokémon easier to catch. Checking for eg. a 3/255 four times gives a lower chance than checking for it three times. Eridanus (talk) 16:34, 24 August 2014 (UTC)

Is the Information for Generation VI Truly Missing?

I may be mistaken with regard to most of this, but in my experience, the Generation VI games seem to use basically the same formula to calculate modified catch rate as Generation V, except for the following differences: there are no longer Pass Powers that increase catch rate, but instead an O-Power can increase catch rate using different coefficients applied in the same part of the formula; and there is no longer a dark grass factor (maybe a flower factor in X and Y?). I know that Pokémon are able to break out of Poké Balls after two shakes, suggesting that the game performs four shake checks, but is there evidence to suggest that the formula that calculates shake probability is different in Generation VI than it was in Generations III-V? Now, what I'm trying to figure out by posting this topic is what we suspect works in ways we do not understand in Generation VI. What is there to research, and how would we go about doing this research? I would happily help out with this research in any way I can. Superbreeder 23:53, 3 December 2014 (UTC)

The issue isn't that we suspect it works differently somehow; it's that nobody has analyzed the capture routine in the code for the sixth-generation games, so we can't actually know how it works the way we do for the previous games. It's quite likely that it works exactly as you suggest, with the same method as gen V except with four shake checks, but probabilistic formulas are essentially impossible to figure out reliably by experimentation. That said, it could be useful to gather a lot of data just to see if the probabilities seem to match up with what we'd expect if it's gen V with four shake checks. Dragonfree (talk) 02:32, 4 December 2014 (UTC)
Thank you for your thorough reply, Dragonfree. Your suggestion to test if the probability is what it would be if Generation V performed a fourth shake check is probably the best path we can take, so I might try to do the experimentation on my own as I like to think I have a fair bit of skill when it comes to collecting, managing, and analyzing data. I think I may use a Pokémon which I may find easily and which has a fairly low catch rate to test so that it won't be guaranteed to be caught in a Quick Ball (i.e. I can attract Skarmory by leading with a Pokémon with Magnet Pull, and Skarmory's catch rate is low for a non-legendary Pokémon at 25). Also, I can record the number of shake checks the ball passes in each attempt just in case there was a change to how the games calculate that. I don't know exactly how many data points I'll collect, but probably between 1,000 and 5,000 to reduce error as much as possible. If I get conclusive data, I'll put my findings under this talk page topic. Perhaps there are other users who would like to help test this as well? Superbreeder 07:40, 4 December 2014 (UTC)

Critical catch shakes in Gen VI

Recently the critical capture section was edited to say that Gen VI has two shake checks on a critical capture. Either someone must have looked at the code/debugged the process, or someone saw two shakes on a critical capture. I doubt it was the former, though (and if it was, the source should be cited). Which leaves the latter...

I can't see how it could be the latter, though. As far as I remember, critical capture in X/Y did one shake. Did ORAS perhaps change this? Can someone with ORAS confidently say how many times the ball shakes on a critical capture? Tiddlywinks (talk) 16:43, 9 December 2014 (UTC)

Critical captures in ORAS definitely only do one shake, like in Gen V. However, do note that when normally when a ball shakes once and then breaks, it means the ball failed the second shake check - the first happens before any shakes. This is unlike Gen V critical captures, where the ball always shakes once and only then does the single shake check. So it is possible that a) the editor is right and the sixth-generation games perform a shake check both before and after the shake on a critical capture (and thus a failed critical capture can either fail before or after the shake), or b) the one shake simply confused the editor into thinking two shake checks were involved based on their understanding of what shakes normally mean. Presumably it would be best to ask them. Dragonfree (talk) 17:36, 9 December 2014 (UTC)
Since Pokémon visited my talk page to inform me of a comment on Dragonfree's talk page responding to this issue, I would like to "move" it here so that any of us (or anyone else) can freely respond without having to do so on a single user's talk page.

Well, my source is my own experience. I saw Pokémon several times breaking out after two shakes though critical capture. The first time I was surprised, because I read on this page before that with one shake the capture would be sure. But I definitely saw Pokémon breaking out while critical captures after both first and second shakes, so it's clear to me, that there must be two shake checks.
(Furthermore I saw them breaking out within all four different shake steps, so there must be also four all in all.)
But what Tiddlywinks recently has done is muddle. He also changed the probability for the non-critical capture for different generations which should be wrong. Regardless of three or four shakes - the whole probability remains the same. (0.39% in the example) --- Pokémon Questions? -- 13:45, 10 December 2014 (UTC)

First off: I cannot help but doubt what you think you saw. I can only think you are mistaken that it was a critical capture. I would like to hear from someone else that it is possible for two shakes to occur in a critical capture. (Also, can you say whether you saw it in XY or in ORAS?)
(FWIW: the 0.39% thing has reared its head again on a new comment from Pokémon on my talk page. I will attempt to address it there.) Tiddlywinks (talk) 15:38, 10 December 2014 (UTC)

The editor - me - has seen both situations while critical capture: breaking after one and after two shakes. It would also make sense, because there are totally four checks again. I saw that in X & Y. But I see, as I have no solid proof...
So and why should the formula of b in GenV contain 65536 (=2^16) instead of 65535 (=2^16-1) like it always does? 65536 also is inconsistent with the other generations.--- Pokémon Questions? -- 15:56, 10 December 2014 (UTC)

Alright, if you want to discuss 65536 vs 65535 here... I agree with you. Thank you for pointing out the "other generations" this time. The Gen III-IV formula is the same as the Gen V formula (after some transformation, and ignoring 65536 vs 65535), so I agree that it should probably be 65535. If you had pointed this out in your edit comment instead of just suggesting that there's hardly any difference (which, by itself, is not at all a good reason to make a change), I wouldn't have reverted your edit, so please try to take more care in the future. Tiddlywinks (talk) 16:03, 10 December 2014 (UTC)
Uhm, I just copied my statement, so indeed I already pointed the "other generations" out. And just for my understanding, where did I suggest "that there's hardly any difference"? --- Pokémon Questions? -- 18:21, 10 December 2014 (UTC)
No, it's definitely 65536 in the fifth generation, not 65535. The b formula also definitely does take a fourth root (actually two square roots), not a third root, despite that there are only three shake checks. This is information gleaned from reading the actual game code; Ultimate Pokémon Center did the original analysis, and a_magical_me later independently did another full analysis and corrected a couple of mistakes. My website's explanation incorporates magical's corrections. Please don't make edits based on vague common-sense feelings about what seems right when there are known facts at hand.
Meanwhile, Pokémon, you do realize critical captures that succeed only show one shake? Are you suggesting it sometimes shows a whole extra shake only if you fail? That sounds quite unlikely, especially since if they did want to incorporate two shake checks into critical captures, the logical way to do it would be like with regular shake checks, where one happens before the first shake and the second happens just after it. I'm sorry, but unless you can provide something more solid than anecdotal experience, it's more likely that you just mistook a non-critical capture for a critical, one way or another. I've seen people swear they personally saw completely impossible things on their Pokémon games hundreds of times before, so I'm inclined to take "This happened to me once" stories with a grain of salt - nothing against you personally, but human perception and memory can be pretty flawed. Dragonfree (talk) 18:34, 10 December 2014 (UTC)
Sorry, Dragonfree. It's not much of an excuse, but I didn't really know where I could find a reliable reference.
@Pokémon: I meant that you didn't point out "other generations" in your edit summary; but in your comments afterwards, you have. Your edit summary said, "Seriously, the fraction is so tiny, nobody can read it without grand zooming..." The only sense I could make of that comment was that the difference between 65536 and 65535 was very small. But perhaps that's not what you meant. Regardless, it's not really important now. Tiddlywinks (talk) 19:01, 10 December 2014 (UTC)
I meant the size of the fraction. :) Just the size. It's too tiny to read.
@Dragonfree: Thank you for the pages, that's what I wanted to see. Although I do not understand why the catch rate calculator on your website needs the level of the Pokémon? The level is absent in the formula. --- Pokémon Questions? -- 19:54, 10 December 2014 (UTC)
The calculator uses the level to calculate the Pokémon's actual HP, mostly significant if you select the "Exactly 1 HP" option - it makes a bit of a difference whether the Pokémon has one out of 20 HP or one out of 200 HP. Not much of one (in the newer games, anyway; in the second-generation games there is some glorious wonkiness involving underflows where the exact HP can make a massive difference), but I like precision. Dragonfree (talk) 20:58, 10 December 2014 (UTC)
From the level alone you can't know the max HP, thats no precision. And percent is percent, neither it is needed to know the exactly HP nor the level. The whole formula has no level inside, so it can't make a difference. And if it makes a difference, it must be explained right here in this article. --- Pokémon Questions? -- 23:40, 10 December 2014 (UTC)
It's not the level alone - we also know the species, and thus its base HP, and wild Pokémon's EVs are always zero. The only remaining variable needed to determine the max HP is the IV, and the calculator calculates the result for each of the 32 possible IVs. By default the calculator then averages the results, since each IV is generally equally likely, but if you check the "Show detailed report?" box, you'll see the exact results for each HP IV.
Percent is percent, yes, but 1 out of 20 HP is 5%, while 1 out of 200 HP is 0.5%. Like I said, it's only actually significant at exactly 1 HP. Usually you don't actually know the Pokémon's exact current HP, so there's an unavoidable margin of error there either way, but by calculating the actual max HP we can get guaranteed exact results at full and 1 HP (this is why I have a special "exactly 1 HP" option, separate from "1%"). And while the results at full HP will be pretty much identical no matter what the actual max HP is, there are rounding errors that this allows for taking into account accurately, which I like to do because as I said, I like precision.
Please consider that maybe I know what I'm talking about. I've spent a lot of time on these pages and calculators; I assure you I didn't just throw the level in there for no reason. Dragonfree (talk) 00:18, 11 December 2014 (UTC)
Of course I know what you mean. For 1 HP remaining the level is a factor. But as long as you don't know the IV exactly, it's not precise, right? ;) Yes, it's close enough.
But I wonder why the result is also influenced, when I set neither 100% nor 1 HP but e.g. 40%? A percentage is already most precise and independent from the level! I have seen there differences of over three percent between level 1 and 100 which is a large amount and no rounding errors. Just want to understand that phenomenon and why I can't calculate these results with the formulas on Bulbapedia... --- Pokémon Questions? -- 11:29, 11 December 2014 (UTC)
Ah, that's just because when you set a percentage, the calculator uses it to come up with an actual integer current HP value to use in the calculation, and at very low max HPs that can introduce a slightly significant error. So, rounding errors, but not in the formula per se. (Actually, it was a bigger rounding error than it needed to be; I just made a small change that reduces it.) In general it's always going to be a bit fuzzy when you're not at 100% or exactly one HP, because both the HP bar itself and the player's approximation of how much of it is filled inevitably introduce a degree of error. I'd rather have it show the actual results for a reasonable guess at the exact HP than make up a general fuzzy result for that percentage of HP, though. The calculators simulate the calculations the game performs very exactly; having the HP part just rely on it being roughly such-and-such kind of defeats the point. (Besides, of course, that this way the result is exact at 100% or exactly 1 HP without having to special-case it.) Dragonfree (talk) 13:14, 11 December 2014 (UTC)

Just caught a Lugia in red health underwater after using Dive in a Dive Ball.

I just caught Lugia in red health in ORAS so you have to use dive to catch it and it worked first time in a Dive Ball. Does anyone know the chances of this happening? --Hydreigonfan1 (talk) 18:47, 10 December 2014 (UTC)

Since it's in Gen VI, technically: No, not for sure. But it's very likely the same as Gen V. This might be a better question for the forums, though... Tiddlywinks (talk) 19:04, 10 December 2014 (UTC)
I'd say it's more likely to be the same or just about the same as in Gen IV, actually, since it does look like Gen VI does four shake checks on a regular capture like Gen IV. But yes, the exact mechanics of capture in the sixth-generation games are currently unknown. Dragonfree (talk) 00:21, 11 December 2014 (UTC)

rounding of a

Is the value for "a", the modified catch rate, rounded down/up before put into the equation for "b", the shake probability?

For example, If a great ball is used on a Kyogre (catch rate=5) with full health, the equation becomes a=5*1.5/3=2.5

would a=2.5, or be rounded down to 2, or up to 3 before put into the equation for b. Zombiedude347 (talk) 22:12, 28 December 2014 (UTC)

Rounding in the games usually happens down. Tiddlywinks (talk) 22:16, 28 December 2014 (UTC)
The final result of a is always rounded down to the nearest integer. Dragonfree (talk) 22:28, 28 December 2014 (UTC)
Note, however, that if you're thinking of ORAS, they changed Groudon and Kyogre's catch rate to 3. And if you're thinking of R/S/E, the value is rounded down at every intermediate step in the calculation as well. Dragonfree (talk) 22:33, 28 December 2014 (UTC)
In OR/AS, a is rounded to the nearest multiple of 1/4096. --a_magical_me (talk) 00:25, 29 December 2014 (UTC)
Right, yeah, I misremembered. Was probably thinking of the critical capture value. Dragonfree (talk) 01:09, 29 December 2014 (UTC)
So, in my example, for a would equal 2.5=(2+2048/4096), or if using the current catch rate, a=3*1.5/3=1.5=(1+2048/4096)Zombiedude347 (talk) 15:46, 29 December 2014 (UTC)
Yes, that's the gist of it. Dragonfree (talk) 19:06, 29 December 2014 (UTC)

Are we sure the shake probabilities for Gen III-VI are correct?

And I don't mean just numerically correct--I ask because, the formula written down for Gen III-IV is: b = 1048560 / sqrt(sqrt(16711680/a)); which is weird, since it uses numbers that require 3-bytes to represent. It is made even weirder when you consider that the formula there is exactly equivalent to: b = 65535 / sqrt(sqrt(255/a)); which takes numbers of no more than 2-bytes, which makes a lot more sense, and unless the former was ripped straight from the code, seems closer to what the function actually would be (since it takes up less memory and uses numbers on a similar scale found elsewhere in the mechanics).

This also makes me want to ask if the shake probabilities on Gen V and Gen VI don't have a small typo, since both have similar formulas to the above (though Gen VI has a denominator of (255/a)^0.1875), but instead of 65535, they have 65536, which is 1 off, but is 17-bit to 65535's 16-bits and that would be...inelegant. It would break the symmetry, since if it's 65535, then Gen III-V would all have the same shake probability function, and it seems a little silly to tweak it by 1 in a way that would require an extra byte of memory for the input, and right before a more substantial tweak in the very next gen. But I don't know--for all I know, that could be faithfully ripped straight from the source code.

Xovvo (talk) 20:46, 23 February 2015 (UTC)

Yes, they are correct, and all of these numbers are indeed taken straight from the actual code.
Your Gen III/IV alternative formula is actually not exactly equivalent, because the square roots and divisions prior to Gen V are integer operations, i.e. they always round down: if they used the shorter version, then any a of 16 or above would actually give the same b, which would be completely absurd. (255/16 gets rounded down to 15, the square root of which is rounded down to 3, the square root of which is rounded down to 1, and we end up with a b of 65535, exactly like if a were 255.) Effectively, Game Freak took the formula they wanted and multiplied by 16 both above and below the line, in order to have bigger numbers to work with in the calculation that would result in less drastic rounding errors. (There are still fairly major rounding errors, mind you; any a of 200 or above still results in a b of 65535.)
The reason Gen V-VI use 65536 and not 65535 is that there is a tiny chance for the Pokémon not to be caught if b is 65535; presumably they wanted b to be able to be 65536 all along but originally used 65535 exactly because 65536 can't be stored in a two-byte register. In Gen V onwards they're using bigger fixed-precision numbers where they can fit 65536 in just fine anyway. Dragonfree (talk) 00:21, 24 February 2015 (UTC)

Trivia First Bullet Point is Vague and Needs Explaining

I made an edit by adding {{incomplete}} to the trivia section that needs further explanation of how the button presses affect catch rate in Generation I games. User:Abcboy removed claiming he clarified it but I see no clarification. Needs specifics or citations if the article will state such a claim! Why does catch rate get affected by button combinations? Which button combinations work? How much does it affect catch rate? Which games does it work for if not all? --Wildgoosespeeder (talk) 01:45, 17 March 2015 (UTC)

There are no specific button combinations that affect catch rate in any specific way; it's simply that in the first-generation games, the random number generator is advanced when buttons are pressed, so if you want the random number generator to hit a particular number when it does the calculation and you know which numbers are coming up when, such as when doing a tool-assisted speedrun, pressing buttons will advance the RNG further. It's not something that's ever relevant to normal gameplay in any fashion. Dragonfree (talk) 02:01, 17 March 2015 (UTC)
Also, FWIW, I kind of want to add that the Trivia section may be the last place that should have an "incomplete" template anyway. It's called Trivia for a reason. If it were me, the talk page here would have been my first resort. Tiddlywinks (talk) 02:15, 17 March 2015 (UTC)
Also, what ABCboy added was, pretty much, "as button input could slightly influence the random number generation in the catch rate formulas". This was his attempt at clarification. The entire trivia point is Greek to me, personally, as a casual player only, but I can see how it would be of interest to the right party. I was also going to comment that we don't put "incomplete" in the trivia section, but all the edit conflicts (I got two) got Tiddlywinks' pointing it out in first. CycloneGU (talk) 02:17, 17 March 2015 (UTC)

'Status value' in Generation I

In the Generation 1 algorithm, step four is

Otherwise, if N minus the status value is greater than the Pokémon's catch rate, the Pokémon breaks free.

What is the status value? It isn't mentioned anywhere else in the page.

The only thing I saw that I think it could be referring to is the numbers in step three:

The Pokémon is caught if...
It is asleep or frozen and N is less than 25.
It is paralyzed, burned, or poisoned and N is less than 12.

If that is the case, step three can definitely be worded better. Meemo16 (talk) 20:34, 8 March 2016 (UTC)

Problem should now be fixed. SirFinkleBottom 21:29, 8 March 2016 (UTC)

Number of shakes in Gen 1

In gen 1, I saw Pokémon who broke free when they were supposed to get caught. I don't get it. Does that mean they can break free at the fourth shake ? -- Braviapert 15:20, 24 April 2016 (UTC)

In Generation I, there are only two states as far as I know: the Pokemon is caught or it breaks after a fixed amount of shakes (or it outright avoids the Ball if it's really low). If it breaks, the amount of shakes is dependent on how likely you are to capture it. Eridanus (talk) 14:01, 25 April 2016 (UTC)

Catch rates for SM

Does anyone have any info on the formula used for Sun or Moon? Prowlcorp (talk) 02:03, 26 January 2017 (UTC)

How it is calculated

Looking at page I can't understand much so I ask a question. How do you calculate probablility for catching Pokemon with a Poke Ball and full health? Just give me a formula with catch rate written as x.--Dominikololo (talk) 18:25, 19 September 2017 (UTC)

I can't belive it's so easy (x/765).--Dominikololo (talk) 17:16, 23 September 2017 (UTC)

Generation III-IV Shake Probability

In the Shake Probability formula for Gen III-IV I see the sqrt used twice. Is this because the game actually does it like that or could it be written like a root 4 of the given division? Fkbm (talk) 09:10, 16 April 2019 (UTC) fkbm

The game actually does it that way. It can be replaced by a fourth root, since the result is identical (the intermediate flooring to an integer never changes the final result), but the game only has a square root function. Aaaaaa123456789 (talk) 09:21, 16 April 2019 (UTC)

Catch rate for Gen 8

So it's pretty obvious the catch rate is different in Gen 8. Does anyone know how it really works? The level of the Pokemon definitely matters to the point where it's sometimes impossible to catch a Pokemon even 1 level above you. And for that matter, how do Raid Battle catch rates work? Are they predetermined at some point or something? --Koetsu (talk) 21:04, 8 December 2019 (UTC)

This definitely requires more research -- after playing through the game I never once got any "obvious" impression of the catch rate being different from previous generations. (Of course, I was usually about level-matched with the wild Pokemon in question.) Max Raid Battle catch rates are (by now) documented on their own page, with the host having a higher catch rate than guests and the base rate being different for Gigantamax forms. --Stratelier 02:06, 23 August 2020 (UTC)
Okay, here is a "quick" experiment:
These Pokemon all have a catch rate = 255 (expected catch probability: 44% per throw)
  • Throwing a standard Poke Ball on turn 1 until caught
After throwing 100 Poke Balls, my data:
Normal throws (catch/miss ratio): 55:7 (88% success)
Critical throws: 36:2, or 95%
This was approximately 2x the expected catch rate. Hmm...
--Stratelier 04:03, 23 August 2020 (UTC)

Time for experiment #2. This one involves a LOT more setup, but:

  • Area: Wild Area, Bridge Field
  • Target: Lv.60 Zigzagoon (catch rate = 255)
  • Lead Pokemon: any Lv.1 Pokemon (I have the Pokemon Nursery set up with a breeding pair for this purpose)
  • Other party members (in case this is relevant): a Lv.45-50 Coalossal
  • Throwing a Poke Ball on turn 1 until caught (or unless lead Pokemon faints)

And my data as follows (using 100 standard Poke Balls)

Normal throws (catch/miss ratio) = 42:44 (49%)
Critical throws = 12:2 (85%)

Which is close to the expected catch rate. Also note a much lower incidence of critical throws this time (1:7 versus 2:5). Hmmm...

(This also gives me a huge supply of Lv.60 Zigzagoons for performing a level-matched experiment later) --Stratelier 20:29, 26 August 2020 (UTC)

So if I'm understanding this correctly, the level is affecting the catch rate? Doesn't crit rate increase the more the Pokedex is filled? Would the results skew to more misses if you have a very incomplete Pokedex, or does it just affect the chance of a crit happening? --Koetsu (talk) 05:00, 27 August 2020 (UTC)

Dive Ball doesn't actually work while Surfing or Fishing in FRLG

Looking at the pokefirered decompilation, the check is the same as in RSE: [Source] - unsigned comment from AsparagusEduardo (talkcontribs)

Generation I "Great ball better than Ultra"

Upon reading the Gen I article i got very confused by this:

"Due to the nature of the algorithm, Ultra Balls will only perform better than Great Balls on Pokémon whose capture rates are above 55 and below 200 in Generation I. Ultra Balls increase the overall chance of capture by as much as 20% in comparison to Great Balls for Pokémon near the center of that range."

This is not at all what the full algorithm description says, neither what the formula says. The only benefit of great ball is on step 6 when the pokémon has more than 1/3 hp. I would guess that the contributor forgot to say that his statement is only valid against 100% hp pokémons? Which is not a very useful info anyway. Grogir (talk) 14:37, 31 October 2020 (UTC)

Failed to parse

Is it just something on my end or is this article littered with "failed to parse" error messages for displaying math? Landfish7 02:34, 14 January 2022 (UTC)

I mean I don't see that. I'd say try again today, I know Bulbagarden overall was having website issues of some sort yesterday. Karasuhebi (talk) 18:37, 14 January 2022 (UTC)
You're probably right. Looks good now! Landfish7 05:37, 17 January 2022 (UTC)

Gen 8 level modifier

Gen 8 added a L modifier based on the level. The section should explain what it means, in addition to the formula. Does it mean that higher levels are harder to capture? Up to what level? By what rate? What's that 70 doin in the formula? Mateussf (talk) 14:56, 30 March 2022 (UTC)

Gen 8 formula errors

There appears to be a couple of errors in the Gen 8 formula. Firstly, the value of 'a' seems to be too large, possibly by a factor of 4096. Secondly, the species based catch rate is referred to as 'ratemodified', yet there does not appear to be any modification. If I am not misunderstanding, it should simply be called 'rate'.

Qwertyuiop13 (talk) 23:30, 14 December 2022 (UTC)

Return to "Catch rate" page.