About Gen 2 Capture Odds
Generation 2 catching looks simple during play. The math is not simple. The game first changes the species catch rate with the selected ball. Then it mixes that value with current HP, maximum HP, and status. The result is a final capture rate called X in this calculator.
Why The Calculator Helps
Small changes can matter. A low HP target usually gives better odds. Sleep and freeze add a fixed bonus. Other major status effects look useful, but they do not raise the Gen 2 chance. That detail surprises many players. It also changes item planning during long routes, legendary hunts, and challenge runs.
Ball Choice Matters
Each ball has its own behavior. Great Ball and Ultra Ball multiply the base rate. Heavy Ball adds or subtracts points based on weight. Lure Ball helps when fishing. Fast Ball only helps a few species in these games. Love Ball checks same species and same gender. Moon Ball acts like a normal ball in standard play because of a bug. Level Ball is special. It skips the HP formula and uses its modified rate directly.
Good Input Practice
Use the exact max HP when possible. Use the exact current HP after damage. If you only know a percentage, estimate current HP first. Keep the species catch rate within the allowed range. For custom encounters, read the warning notes, especially when huge HP values are used.
Reading The Result
The single throw chance shows the chance for one ball. The attempt chance shows the chance after several throws. Expected balls is an average, not a promise. Sometimes a catch happens immediately. Sometimes many balls fail. The fifty percent and ninety five percent lines help plan inventory.
Planning Strategy
Lower HP before throwing most balls. Use sleep or freeze when safe. Select special balls only when their conditions really apply. Compare several cases before saving. Export the report when you want to keep notes. The calculator is useful for casual play, route planning, speedrun practice, and research testing. It gives transparent steps, so you can see why a ball performs well or poorly. Repeat tests help compare rare targets quickly. Notes support route plans and custom rule sets well.