Games & scoring / Ratings
Elo Rating Calculator: Expected Score and Rating Change
Work out the expected score between two players and the new Elo ratings after a win, draw, or loss, with a K-factor of 10 to 40, for chess and other games rated by Elo.
Elo Rating Calculator: Expected Score and Rating Change: The expected score is 1 ÷ (1 + 10^((opponent − you) ÷ 400)): at 1600 against 1400 it is 0.76. The rating moves by K × (result − expected), so with K = 20 a win adds 4.8 points and a loss costs 15.2, leaving 1584.8. Runs 100% locally in your browser with zero server file uploads.
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| Result | Change | New rating |
|---|---|---|
| Win | +4.8 | 1,605 |
| Draw | −5.2 | 1,595 |
| Loss | −15.2 | 1,585 |
The expected score is 1 ÷ (1 + 10^((opponent − you) ÷ 400)): a 200-point favourite is expected to score about 0.76. After the game your rating moves by K × (result − expected), where a win scores 1, a draw 0.5, and a loss 0. FIDE uses K = 40 for new players and juniors under 2300, 20 below 2400, and 10 once a player has reached 2400; online sites and other games use their own K or other systems such as Glicko.
The 400-point scale
A difference of 400 points means the stronger player is expected to score about 0.91, and 200 points about 0.76; equal ratings mean 0.5 each.
Running a tournament
To pair players for a knockout, use the tournament bracket.
How to use it
- Enter your rating and your opponent's.
- Choose the result and the K-factor.
- Read your new rating and the change for every result.
Privacy & limitations
Everything is calculated in your browser.
Related tools
Frequently asked questions
What K-factor should I use?
FIDE uses 40 for a player's first 30 games and for players under 18 rated below 2300, 20 for others below 2400, and 10 once a player has reached 2400. National federations and online sites set their own.
Why did I gain so little for a win?
Beating a much lower-rated player was expected, so the result adds little; beating a stronger player adds more.
Do online chess sites use Elo?
Many use the related Glicko systems, which also track how certain a rating is, so their changes differ from this calculator.
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