Chess Elo Rating Calculator
Calculate your new chess Elo rating after one game or a whole tournament, with expected score, rating change, FIDE K-factors and performance rating.
The Elo system rates chess players by comparing the score they actually make with the score their rating predicted. Beat a stronger opponent and you gain more than for beating a weaker one; lose to a weaker opponent and you drop more. Enter your rating, K-factor and the games you played, one or a whole tournament, to get your new rating, expected score, performance rating and the change from each game.
How to use this tool
- Enter your current rating.
- Choose your K-factor. FIDE uses 40, 20 or 10 depending on experience, age and rating.
- List each game as the opponent's rating and the result: win, draw or loss.
- Keep the FIDE table and the 400-point rule for official FIDE ratings, or switch to the Elo formula for the textbook calculation.
Formula
E = 1 / (1 + 10^((Ropp − R) / 400)) · New rating = R + K × (S − ΣE)
E is the expected score for one game (0 to 1), S is your total score and K sets how fast ratings move. FIDE replaces the curve with table 8.1.2, rounded to 0.01. Performance rating is the rating at which your expected score would equal your actual score.
Example
Using the Elo formula, a player rated 1613 with K = 32 loses to 1609, draws with 1477, beats 1388 and 1586, and loses to 1720. The expected scores are 0.506, 0.686, 0.785, 0.539 and 0.351, totalling 2.867, but the actual score is 2.5. The new rating is 1613 + 32 × (2.5 − 2.867) = 1601.3, a drop of about 11.7 points, matching the well-known Wikipedia example's 1601.
Frequently asked questions
Which K-factor should I use?
Under FIDE rules: 40 until you have completed events with 30 games, and until the end of the year you turn 18 while rated under 2300; 20 while your rating stays under 2400; 10 once your published rating has reached 2400. FIDE also lowers K when K × games in one rating period would exceed 700.
What is the 400-point rule?
FIDE counts any rating gap above 400 as exactly 400, so beating a much weaker player still earns a little. Since 1 October 2025 it applies only to players rated below 2650; stronger players always use the real gap.
Are Chess.com and Lichess ratings Elo?
No. Both use Glicko-based systems that also track how reliable your rating is, so their changes will not match this calculator.
What is a performance rating?
The rating that would have made your actual score the expected one. Scoring 50% against opponents averaging 1600 gives a performance of about 1600.
Sources
Last updated: 2026