Chess Elo Calculator

1. Enter your current rating from your FIDE, USCF, or Chess.com profile.
2. Enter your opponent's rating. For exact accuracy, use the rating they had before the game, not after.
3. Select the game result: Win, Draw, or Loss.
4. Choose the K factor: 40 for new players or juniors, 20 for standard adult ratings under 2400, 10 for masters. Chess.com uses different K values per time control (rapid 32, blitz 24, bullet 16).
5. The calculator shows your new rating, point change, and the expected score you would've been predicted to earn (e.g., 35% expected against a stronger player).

Elo (created by Arpad Elo in the 1960s) ranks players by predicting the probability that one player will beat another based on their rating gap. The formula adjusts ratings after each game based on the gap between expected and actual result.

Expected Score = 1 / (1 + 10^((Opponent − You) / 400))

Score: Win = 1, Draw = 0.5, Loss = 0

New Rating = Current Rating + K × (Actual − Expected)

Example: Rated 1500, playing a 1600-rated opponent, with K=20.

• Expected = 1 / (1 + 10^(100/400)) = 1 / (1 + 1.778) = 0.36 (36% chance)
• If you win (score = 1): change = 20 × (1 − 0.36) = +12.8 → new rating 1513
• If you lose (score = 0): change = 20 × (0 − 0.36) = -7.2 → new rating 1493
• If you draw (score = 0.5): change = 20 × (0.5 − 0.36) = +2.8 → new rating 1503

If you play on chess.com, lichess, and FIDE-rated tournaments, you'll notice your rating varies by 200-400 points across them — sometimes more. This isn't random; each platform calibrates differently.

Three things to know about online vs over-the-board ratings:

• Online ratings inflate. Most players are 100-300 points higher online than in tournaments. Online games favor pattern recognition and time management; tournament games favor calculation and stamina.
• Time control matters. A player rated 1800 in rapid (10-30 min) often falls to 1500 in bullet (1-3 min). Tactical accuracy degrades fast under time pressure.
• Lichess and Chess.com use different math. Lichess uses Glicko-2 (which includes a rating deviation factor); Chess.com uses traditional Elo. The same player will rate differently on each by 50-150 points consistently.