Elo Rating Change
Rating change after a chess or tennis match.
Rating change
+12.8
New rating: 1413
Expected score (probability of winning): 36.0%
Actual score: 1
Formula: change = K × (actual − expected)
Standard Elo system used in chess (FIDE, USCF, chess.com), tennis, Go, and online gaming. The K-factor controls volatility: higher K means bigger swings. Beating a much stronger opponent gains a lot; beating a weaker one barely moves your rating.
About
Enter your rating, your opponent's rating, the K-factor, and the result. Get your new rating and the change. The Elo formula gives you more for beating stronger players and less for beating weaker ones.
How to use
- Enter your and opponent's ratings.
- Pick K-factor and result.
- Read rating change.
FAQ
What K-factor should I use?+
FIDE: 40 for first 30 games or under-18s under 2300, 20 for everyone else, 10 for top players (2400+). USCF and chess.com use slightly different values. The number determines how volatile your rating is.