FIDE rating calculator
Enter your rating and each game's opponent and result. You'll see the points you gain or lose, game by game, worked out the way FIDE does it.
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How FIDE rating changes are worked out
Every rated game has an expected score based on the rating difference between you and your opponent. Facing someone 200 points lower, you're expected to score about 0.76; facing someone 200 points higher, about 0.24. After the event FIDE adds up what you actually scored and what you were expected to score:
Rating change = K × (your total score − your total expected score), rounded to a whole number.
Two rules keep things fair. A difference of more than 400 points is treated as 400, and if K × the number of games would be more than 700, K is lowered until it isn't. This calculator applies both.
Track every student's rating without a spreadsheet
If you coach, you already know the routine: tournament results arrive, and somebody updates a sheet of ratings by hand. On Chessido your students' games, puzzles and progress live in one place, you can run your own rated academy tournaments with Swiss pairings and publish them to Chess-Results, and parents get clear progress reports. More free tools: chess tools for coaches.
FIDE rating — common questions
How is a FIDE rating change calculated?
For every game, FIDE compares your score (1, ½ or 0) with the score expected from the rating difference. The change is K × (total score − total expected score), rounded to a whole number. Beat higher-rated players and you gain more; lose to lower-rated players and you drop more.
What K-factor should I use?
K = 40 for a new player until they have 30 rated games, and for every player under 18 whose rating is below 2300. K = 20 for everyone else below 2400. K = 10 once your published rating has ever reached 2400.
What is the 400-point rule?
A rating difference of more than 400 points is counted as exactly 400, so beating a much weaker player still gains a little and losing to a much stronger one costs a little.
Why does my K-factor drop in a long event?
If K multiplied by the number of games in a rating period is more than 700, FIDE lowers K to the largest whole number for which K × games is still 700 or less. That keeps one long event from moving a rating too far.
Is this the same as the official FIDE calculation?
It follows the FIDE rating regulations and gives the same result in almost every case. FIDE's expected-score table is rounded to two decimals, so a result can occasionally differ by a single point — the published FIDE list is always the final word.
Can my students track their rating progress?
Yes. On Chessido every student has a progress page with their games, puzzles and ratings, and coaches can run their own rated academy tournaments and send results to Chess-Results.
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