Work out elo rating change instantly with clear inputs, formula shown and shareable results.
Expected points are the per-game expectancy times games played, and the change is K times actual minus expected; performance rating inverts the Elo curve on the score percentage. Performance rating shows the level you actually played at, independent of your current rating, which is the fairer measure of a single tournament.
Expected points
expected = games x 1 / (1 + 10 ^ ((opponent average - rating) / 400))
Performance rating
performance = opponent average - 400 x log10(1 / score fraction - 1)
expected = games x 1 / (1 + 10 ^ ((opponent average - rating) / 400)). Expected points are the per-game expectancy times games played, and the change is K times actual minus expected; performance rating inverts the Elo curve on the score percentage.
Performance rating shows the level you actually played at, independent of your current rating, which is the fairer measure of a single tournament.
Enter current rating, average opponent rating, games played, points scored. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.