Elo Rating Calculator
The Elo rating system is the standard method for calculating chess player strength. Enter your rating, your opponent's rating, and the game result to see exactly how your rating changes. Supports FIDE, USCF, Chess.com, and Lichess rating systems with their different K-factors.
Professor Archer says: Your rating is just a number - what matters is the understanding behind it. But if you are curious about the maths, this calculator shows you exactly how the Elo system works. Notice how beating a higher-rated player earns you more points than beating a lower-rated one. That is the elegance of the system.
Features
- Calculate new Elo rating after any game result
- Support for FIDE, USCF, Chess.com, and Lichess systems
- Adjustable K-factor for different rating brackets
- See expected score and rating change breakdown
- Batch calculation for multiple games
Frequently Asked Questions
What is the Elo rating system?
The Elo rating system, invented by Arpad Elo in the 1960s, is a method for calculating the relative skill of chess players. Each player has a numerical rating, and after each game, ratings are adjusted based on the result and the difference in ratings between the two players. A higher-rated player is expected to beat a lower-rated one, so an upset causes a larger rating change.
What is the K-factor in Elo calculations?
The K-factor determines how much a single game can change your rating. FIDE uses K=40 for new players, K=20 for players under 2400, and K=10 for players over 2400. Chess.com and Lichess use different K-factors that can vary based on how many games you have played. A higher K-factor means your rating changes more quickly.
How is expected score calculated?
The expected score is calculated using the formula E = 1 / (1 + 10^((opponent_rating - your_rating) / 400)). This gives a value between 0 and 1, where 1 means you are expected to win every time, 0.5 means the match is even, and 0 means you are expected to lose. Your new rating equals your old rating plus K times (actual score minus expected score).
Why do different platforms use different rating systems?
FIDE, Chess.com, and Lichess all use variations of the Elo system but with different parameters. FIDE ratings tend to be more conservative and change slowly. Chess.com uses a Glicko-based system that adjusts more quickly. Lichess uses Glicko-2, which also factors in rating volatility. This is why your rating on different platforms will differ.