Chess performance rating calculator
Paste your opponents' ratings and enter your score. The calculator shows your performance rating — the rating at which a player would be expected to score what you did — by two common methods, along with the average rating of your opponents.
Runs in your browser: nothing you enter is sent anywhere.
How to use
- Type or paste the ratings of all your opponents in the tournament.
- Enter your score in points (win 1, draw ½, loss 0), for example 3.5.
- Read the performance rating by both methods, the average opponent rating and your score percentage.
With n games, score S, p = S ÷ n and Ra the average opponent rating:
- rule of 400: Rp = Ra + 400 × (2S − n) ÷ n
- Elo formula: Rp = Ra + 400 × log10(p ÷ (1 − p))
Unrated opponents should be left out, along with the points scored against them.
Example
Opponents 1850, 1920, 2010, 1780 and 1900, score 3.5:
- average: 9,460 ÷ 5 = 1,892; score 3.5 / 5 = 70 %;
- rule of 400: 1,892 + 400 × (7 − 5) ÷ 5 = 1,892 + 160 = 2,052;
- Elo formula: 1,892 + 400 × log10(0.7 ÷ 0.3) = 1,892 + 147.2 = 2,039.
Tips
- A performance rating above your own rating means your rating will usually go up after the event.
- Over few games performance rating jumps a lot; one extra draw in a 5-game event moves it by 80 points with the rule of 400.
- To see the rating change from each game, use the Elo rating calculator.
Frequently asked questions
How is performance rating calculated?
The rule of 400 counts each win as the opponent's rating + 400 and each loss as − 400, then averages: Rp = average + 400 × (wins − losses) ÷ games. 3.5 out of 5 against an average of 1,892 is 1,892 + 400 × (3 − 1) ÷ 5 = 2,052 (3.5 points could be 3 wins, 1 draw and 1 loss).
What is the Elo method?
It looks for the rating whose Elo expected score equals your result: Rp = average + 400 × log10(p ÷ (1 − p)), where p is your score percentage. 70 % gives 1,892 + 400 × log10(2.333) = 2,039. It cannot give a number for 0 % or 100 %.
Is this the FIDE performance rating?
Not exactly. FIDE takes the average rating and adds a value from its own table of rating differences for each score percentage, with a cap of 800 points for a perfect or zero score. Results are close to the Elo method in the middle range; check FIDE's table for official norms.
Why do the two methods differ?
The rule of 400 is a straight line: each extra half point adds the same amount, and it never goes more than 400 above or below the average. The Elo formula follows the S-shaped expected-score curve: at 70 % it adds a little less (147 instead of 160 points), at 90 % more (382 instead of 320). Near 50 % both give almost the same number.