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Elo Rating Calculator.

Update an Elo rating from opponent rating, K factor, and match result.

On-device calculationNo signup
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Set your values

Results update as you type.

Expected score: 0.5

Expected score

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Rating change: 16

Rating change

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New rating: 1,516

New rating

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Results update automatically as you type.

Use Cases

Track your chess rating after a tournament

After each game, input your rating, opponent's rating, result, and K factor to see your updated rating instantly.

Example: Player rating 1500, opponent 1600, win, K=20 → new rating 1514.4

Adjust ratings for a local league

League organizers can use this to update player ratings after each match, ensuring fair rankings.

Example: Use K=32 for new players to speed up rating convergence.

Frequently Asked Questions

How is the new Elo rating calculated?
The calculator uses the standard Elo formula: expected score = 1 / (1 + 10^((opponent rating - player rating)/400)). The new rating = player rating + K factor * (actual result - expected score). The result is 1 for win, 0.5 for draw, 0 for loss.
What is the K factor and how do I choose it?
The K factor controls how much a result affects the rating. Higher K means larger changes. Common values: 32 for new players, 24 for intermediate, 16 for advanced. Choose based on your rating pool or organization rules.
Can I use this for chess, esports, or other games?
Yes, the Elo system is used in chess, esports, and many competitive games. As long as you have ratings and a K factor, this calculator updates the rating for any match result.

Tips & Common Mistakes

Tips

  • Use a consistent K factor for all players in your rating pool to maintain fairness.
  • For provisional ratings, a higher K factor (e.g., 40) helps new players reach their true rating faster.
  • Double-check the result: 1 for win, 0.5 for draw, 0 for loss. A common mistake is using 0.5 for a win.
  • If you play multiple games, update your rating sequentially: use the new rating as the player rating for the next game.

Common Mistakes to Avoid

  • Entering the result as a percentage (e.g., 100 for win) instead of 1, 0.5, or 0.
  • Using the same K factor for all players regardless of experience; lower-rated players often need a higher K.
  • Forgetting to update the player rating after each game, leading to cumulative errors.

Last updated: August 13, 2026