Pokémon Catch Rate Calculator (Gen III & IV)

How Pokémon Catch Rates Work in Gen III & IV

In Generation III and IV games, the Pokémon catch rate depends on the species’ base catch rate, current HP, status condition, and the Poké Ball used. The game performs multiple rounding steps, which explains why some low catch-rate Pokémon (e.g. Beldum) show little improvement until HP is reduced further.

Why Catch Rates Sometimes Don’t Change

In Gen III and IV, values are rounded down at each calculation step. For very low catch-rate Pokémon at high HP, ball bonuses may not increase the final result until HP is reduced enough for the bonus to cross a rounding threshold. This calculator correctly accounts for those mechanics.

Shadow Pokémon Catch Rates

Shadow Pokémon in Pokémon Colosseum and Pokémon XD use modified catch mechanics. While most Shadow Pokémon follow standard formulas, certain legendary cases apply fixed values. This calculator reflects standard Gen III/IV behavior.

Frequently Asked Questions

Is this Pokémon Catch Rate Calculator accurate?

Yes. The calculator is based on official Generation III and IV capture mechanics, including correct rounding behavior used by the games.

Why is Beldum so hard to catch?

Beldum has a base catch rate of only 3, the same as most legendaries. At high HP, ball bonuses often do not increase the result due to rounding.

Does Master Ball always work?

Yes. In all Generation III and IV games, the Master Ball guarantees capture.

Does status really help?

Yes. Sleep and Freeze provide the highest bonus, followed by Paralysis, Burn, and Poison.

Last updated: January 2026