Elo Rating Calculator
Enter your rating, the K-factor and your opponents' ratings with the results. You get the expected score for each game and your new rating.
Worked examples
A win against a higher rated player
You 1500, opponent 1600, K 20, win
+12.8, new rating 1513
Expected score 0.36, actual score 1.
An equal match
You 1500, opponent 1500, K 20, win
+10, new rating 1510
Expected score 0.5.
About Elo Rating Calculator
The Elo system, named after Arpad Elo, rates players by how they perform against each other. It is used for chess, and for many other games and sports, to predict results and update ratings. If you are rated 100 points above your opponent you are expected to score about 64% in the long run, and 200 points above gives about 76%. If you do better than expected your rating goes up, and if you do worse it goes down.
The rating change from a game is the K-factor times the difference between your actual score, 1 for a win, a half for a draw and 0 for a loss, and your expected score. Enter your rating, the K-factor and a list of results with the opponents' ratings, and the calculator shows the expected score for each game and your new rating. For a whole event it adds up the expected scores using your starting rating, as a rating list does.
How to use Elo Rating Calculator
- Enter your current rating and choose the K-factor for your rating body.
- List each game on its own line: the opponent's rating, then W, D or L.
- Keep the 400 point limit ticked if your rating body treats bigger gaps as 400.
- Read the expected score for each game, the total change and your new rating.
Common uses
- Estimating a chess rating change after a tournament
- Seeing how much a win against a stronger player is worth
- Rating players in a club ladder
- Checking a rating update from a rating body
Frequently asked questions
How is the expected score worked out?
It is 1 divided by 1 plus 10 to the power of the rating gap divided by 400. At equal ratings it is 0.5. At a gap of 400 points in your favour it is about 0.91.
What is the K-factor?
A number that sets how fast ratings move. FIDE uses 40 for new players and for young players with a rating under 2300, 20 for most players and 10 for players who have reached 2400.
How much do I gain for beating a player rated 100 points higher?
At K of 20 and ratings of 1500 and 1600, the expected score is 0.36 so a win gains 20 times 0.64, which is 12.8 points.
Why might my official change differ?
Rating bodies use their own tables to turn a rating gap into an expected score, round at set points and may apply other rules, so a result can differ by a point or two.
How are draws entered?
Write D, or 1/2, 0.5 or draw. A draw counts as half a point.