Capturing Pokémon is the most important thing in the Pokémon Games. Without it you wouldn't be able to obtain any Pokémon other than your starter. In lamens terms, essentially what you need to do is weaken the Pokémon, pick a PokéBall and throw. However things are much more complicated than that when you get into the code. Of course, if you're using a Master Ball, none of this counts.
There are many deciding factors to the capture of the Pokémon. These include that Pokémon's Maximum HP, Current HP, Status Ailment and it's Catch Rate. The Pokémon's Catch Rate is a number between 0 and 255, the higher the better. You can see the Catch Rates for the Pokémon in our Pokédex.
The formula for determining the capture of the Pokémon is as follows:
CatchValue = ((( 3 * Max HP - 2 * HP ) * (Catch Rate * Ball Modifier ) / (3 * Max HP) ) * Status Modifier
The Capture Value for that is then put through another equation to determine whether or not the Pokémon is to be captured
Catch = 1048560 / √(√(16711680 / CatchValue)) = (220 - 24) / √(√((224 - 216) / CatchValue))
If CatchValue is 255, then capture is guaranteed. However, if not, then the second formula is taken into account. When you throw the Pokéball, and whenever the Pokéball shakes, a random number is generated and if the random number is greater than the value output through the above formula, then capture fails. If however, the random number is lower, then it will go to the next attempt and generate another random number. This is done for three shakes until the capture is complete.
Now the Maximum HP and Current HP of the Pokémon that you are about to catch are obviously not known by you, however that is what the colour coding is for and really the lower the hit points the better the chance
Status Ailments are a completely different amount however. Here is a small table stating the Values that each of the Status Ailments is given
2 (Up to Gen VII)
2.5 (Gen VII)
2 (Up to Gen VII)
2.5 (Gen VII)
Now this does have a major effect on the capture and could definately be the difference between capturing the Pokémon.
The final element of capturing Pokémon is the type of Pokéball that is used. Each of the Pokéballs either multiply or add to the figure before the final division of 256 is done in order to determine the final amount. Below are the Pokéballs and their effects and the amount they actually alter. The Pokéballs from Johto made from apricorns do not give boosts in the Ball Modifier, but rather the actual Capture Rate of the Pokémon, leading up to a maximum possible of 255. Click the Pokéball's icon or name to go to the ItemDex page for locations and more details
|PokéBall||Standard ball used to capture Pokémon||* 1|
|Great Ball||A Ball with a better catch rate than a PokéBall||* 1.5|
|Ultra Ball||A Ball with a better catch rate than a Great Ball||* 2|
|Master Ball||A Ball that never fails at capture||---|
|Safari Ball||A Ball that only exists in the Safari Zone||* 1.5|
A Ball that works better on Bug or Water Types.
If they aren't Bug/Water then * 1. If they are then * 3
As of Pokémon Sun & Moon, the multiplication is *3.5
A Ball that works better on the ocean floor and on Pokémon on water
If used out of water then * 1. If battle field is water then * 3.5
A Ball that works better on Pokémon of a lower level
The Opponent's Level is put into the following formula: (40 - Level)/10. The higher number at the end the better
From Sun & Moon, it works through this formula: (8-0.2*(Level - 1)) with a minimum of 1
|* 1 to 3|
A Ball that works better on Pokémon previously captured.
If the Pokémon hasn't been in your Pokédex then * 1. If it has then * 3.
A Ball that works better the longer the battle has run
Runs off a formula based on how long the Pokémon has been in battle: (Turn + 10) / 10. The longer the better (Maximum of 40 turns to count)
In Sun & Moon it runs off the formula (1+.3*Turn Number), but with 4 as a maximum
|* 1 - 4|
A Ball that can make a Pokémon like you easier.
The Pokémon gains an extra Happiness Value for each Happiness Value that has been obtained
|Premier Ball||A Ball that is given at special events.||* 1|
|Balls introduced in Sinnoh|
|Dusk Ball||A Ball that makes it easier to catch wild in dark places like caves caves and at night||
* 3.5 (Pre-SM)
|Heal Ball||A remedial Pokéball that restores the caught Pokémon's HP and eliminates any status problem.||* 1|
A Pokéball that provides a better catch rate if it is used at the start of a wild encounter
Capture Rate is at 4 for the first turn and 1 any other turn
As of Pokémon Sun & Moon, the capture rate is now *5
|* 4 - * 1|
|Cherish Ball||A Pokéball used to signify special Pokémon||* 1|
|Park Ball||A Pokéball only available in Pal Park. Guarantees capture.||--|
|Balls only in the EntraLink (Generation V Only)|
A dream-like Pokeball that appears suddenly in your bag when you are in the Highlink Forest. It can catch any Pokemon. (BW)
A somewhat different Poké Ball that makes it easier to catch wild Pokémon while they're asleep. (SWSH)
|Balls from Johto|
A Ball that catches Fast Pokémon
If the Pokémon does not flee from battle then * 1. Else * 4
If the Pokémon has a Base Speed stat of less than 100 * 1. Else * 4
A Ball that makes Pokémon like you
The Pokémon's Base Happiness is 200 instead of 70
A Ball that catches Heavier Pokémon Easier
If the Pokémon weighs less than 451.1lbs, the value is -20. If the Pokémon weighs more than 451.1lbs, the value is +20. If the Pokémon weighs more than 677.3lbs, the value is +30. If the Pokémon weighs over 903lbs, the value is +40.
+20, +30, +40
The bigger the difference in level between your Pokémon and the Capture Target, the more likely the capture
If the Pokémon's Level is greater than the opponent's level then * 2. If half your Pokémon's Level is greater than the opponent's Level then * 4. If a quarter of your Pokémon's Level is greater than the opponents Level then * 8
|* 2, * 4, * 8|
This ball works better on Pokémon of the opposite Gender
If the Pokémon is of the same species as yours and the Pokémon's Gender is not the same as the Opponent then * 8. If it is the same or either have no gender then * 1
This ball works better on Pokémon snagged with Fishing Rod
If the Pokémon was obtained through Fishing then * 3, or *5 in Sun & Moon. If the Pokémon wasn't, then *1
This ball works better on Pokémon that evolve with Moon Stone
If the Pokémon evolves with Moon Stone then * 3. If the Pokémon doesn't, then *1
|Sport Ball||A Ball that only exists in the National Park||* 1.5|
|Balls Created by Aether Foundation|
A special Poké Ball designed to catch Ultra Beasts. It has a low success rate for catching others.
If trying to catch an Ultra Beast (Nihilego, Buzzwole, Pheromosa, Xurkitree, Celesteela, Kartana, Guzzlord) it is *5
For all other Pokémon, it is *0.1
And thus with this you are able to make the calculation. What you should get will be a decimal number which is essentially a percentage. The higher the percentage, the more likely you are to capture it. If the number is above 1 then you should get the Pokémon immediately
There is another factor involved. If a Pokémon is an Ultra Beast with the Beast Boost ability such as Nihilego, Pheromosa etc., if they have a non-Beast Ball Poké Ball thrown at them, their catch rate is multiplied by *0.6, reducing the effectiveness by 40%.
A totally new mechanic of capture is the Critical Capture. This feature works like Critical Hits in battle where there is a slight chance that this feature occurs. Critical Capture will be noticed when you throw the Pokéball. It'll make a metal noise, and in Generation V pause in mid-air briefly. When it hits the Pokémon, it will shake once and capture. This cuts two of the four random calculations out of the overal capture mechanic making it more likely to capture the Pokémon. However, it can still fail.
The calculation is done by a simple factor depending upon the amount of Pokémon species you have captured. It will run this calculation based upon the capture value calculated above and will then have another random number based upon the Pokémon you have captured.Critical Capture = floor((255,CatchValue) * Multiplier)
The multipliers are as follows;
Special thanks to Dragonfree for mechanic clarification