Elo Rating Change

Calculate the expected score and new Elo ratings after a match between two players or teams, free online.

Player A rating

Player B rating

K-factor

Result for player A

About this calculator

Expected score E_A = 1 ÷ (1 + 10^((R_B − R_A) ÷ 400)). After a game with result S (1 win, 0.5 draw, 0 loss), the new rating is R_A′ = R_A + K·(S − E_A). Chess federations use K = 10–40; many games use 20–32.