ELO Rating Calculator

Calculate expected outcomes and rating changes based on the ELO system.

Player A Rating

Win probability: 50.0%

Player B Rating

Win probability: 50.0%

K-Factor

Who Won?

How ELO Works

The ELO rating system calculates the relative skill levels of players. A higher rating indicates a stronger player. When a lower-rated player beats a higher-rated player, the rating change is larger. The K-factor determines how much ratings can change per game — higher K-factors mean bigger swings.