Calculate the expected score against an opponent and the new Elo rating after one game.
| Expected score | – |
| New rating | – |
Use this calculator to update an Elo rating after a single game. Enter your rating, the opponent's rating, the K-factor, and the game score.
Expected score = 1 ÷ (1 + 10^((opponent − you) / 400)). New rating = old rating + K × (score − expected). Score is 1 for a win, 0.5 for a draw, and 0 for a loss. Expected score against someone 400 points stronger is 1/11. K = 32 is a common club default; FIDE uses smaller K at high ratings.
This is one game, not a tournament list, pairing table, or performance rating. Chess, go, and many other sports use the same update idea with different K values.
Your rating: Rating before the game.
Opponent: Opponent rating.
K: How fast ratings move. 32 is a usual club K.
Score: 1 for a win, 0.5 for a draw, 0 for a loss.
Expected: Probability of scoring a full point against this opponent.
New rating: Rating after applying the result.
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