Ratings
Elo Gain/Loss Calculator
Quick estimate using the classic Elo formula: Δ = K × (S − E).
Common values: 10 (stable), 20 (standard), 40 (new players).
Output
Expected score (E)
0.500
That’s your predicted score vs this opponent.
Rating change (Δ)
+10.0
New rating (est.): 1510.0
Pro tip
Elo is noisy. Don’t judge progress by one game—track mistakes by category. Use Game Analyzer to find your recurring errors.
FAQ
What is the Elo formula for rating change?
The classic formula is Δ = K × (S − E), where K is the K-factor, S is your actual score (1/0.5/0), and E is your expected score.
What does expected score (E) mean in Elo?
Expected score is the probability-weighted score you’re predicted to achieve against this opponent based on the rating difference.
What K-factor should I use?
If you’re not sure, use 20. Many systems use smaller K for stable players and larger K for new or provisional players (e.g., 40).
Why is my real rating change different from this calculator?
Different platforms (FIDE/USCF/Lichess/Chess.com) use different K-factors, floors, provisional rules, and sometimes different rating systems.
Does Elo measure my true skill?
Not exactly. Elo is a prediction system that becomes a good proxy over many games, but single games and short streaks are noisy.
Want the conceptual version? Read What is Elo in chess.