About this tool
The Pokémon Catch Probability Calculator estimates how likely a throw is to catch a wild Pokémon. Enter the species' catch rate (0–255), its current and maximum HP, the Poké Ball's bonus multiplier, and any status condition, and it returns the per-throw catch chance instantly in your browser.
It uses the classic Generation III/IV capture maths. First it computes the modified catch value a = ((3·MaxHP − 2·CurrentHP) × CatchRate × BallBonus) / (3·MaxHP), then multiplies by the status bonus — ×2 for Sleep or Freeze, ×1.5 for Paralysis, Poison, or Burn, and ×1 for none. If a is 255 or more the catch is guaranteed. Otherwise it derives the shake-check value b = 1048560 / √√(16711680 / a); the probability of one successful shake is b / 65536, and a full capture requires four in a row, so the catch chance is (b/65536)⁴.
The tool also reports the raw catch value a, the single-shake probability, and the expected number of balls you would need to throw (1 ÷ catch chance). Ball bonuses are preset for Poké (×1), Great (×1.5), and Ultra (×2) Balls, with a custom field for any other multiplier — handy for modelling situational balls whose effective bonus you already know.