Elo Calculator for Chess
Enter your rating, your opponents’ ratings and the results to estimate your FIDE rating change.
| Opponent rating | Result | Expected | Change | Remove |
|---|---|---|---|---|
| 0.36 | +12.8 |
Rating change +12.8 → new rating about 1513
The Elo formula, step by step
Say you are rated 1500 and beat a 1600 player with K = 20. The difference is +100, so your expected score is 1 / (1 + 10^(100/400)) ≈ 0.36. You scored 1, so the change is 20 × (1 − 0.36) ≈ +12.8. Had you drawn, the change would be 20 × (0.5 − 0.36) ≈ +2.8; a loss costs 20 × 0.36 ≈ −7.2.
Beating a much stronger player gains more than beating a weaker one, and the 400-point cap means very lopsided pairings never give an expected score above about 0.91.
Frequently asked questions
How is a FIDE rating change calculated?
For each game, the expected score is 1 / (1 + 10^((opponent − you) / 400)), with the rating difference counted as at most 400 points. Your change is K × (actual score − expected score), summed over the games of the rating period.
Which K-factor applies to me?
K = 40 until you have played 30 rated games, and for players under 18 rated below 2300; K = 20 for most players; K = 10 once you have ever reached 2400. Check the current FIDE Rating Regulations for edge cases.
Does it work for Chess.com or Lichess ratings?
Not exactly. Chess.com uses the Glicko system and Lichess uses Glicko-2, which also track how certain your rating is. This calculator follows the FIDE Elo rules used for over-the-board ratings.