FIDE Rating Calculator
Free tool · No account neededYour rating, your opponents, and the change the rating list would actually show. Runs in your browser. Nothing is uploaded.
Enter your published rating, add a row per game with your opponent’s rating and the result, and the calculator works through the FIDE Rating Regulations as written: the expected score for each game comes from table 8.1.2, the development coefficient follows the rules in article 8.3.3, and the total is rounded the way article 8.3.4 says. It also gives the performance rating for the event.
What this tool does
The official table, not the formula
FIDE converts a rating difference into an expected score with a lookup table whose steps round to two decimals. Calculators that use the logistic curve instead disagree by a point or more over a long event.
The 2650 rule
Since 1 October 2025 the 400-point cap on the rating difference applies only below 2650. Above it the real gap is used, which changes what a draw against a much weaker opponent costs.
Every K-factor case
Forty while you are completing your first thirty games, forty for juniors under 2300, ten once 2400 has been reached, twenty otherwise, and the ceiling that keeps K times the number of games at 700 or less.
Performance rating too
The opponents’ average plus the rating difference for your fractional score, from table 8.1.1 — the number tournament reports print.
How to work out your rating change
- 1
Type in the rating you are published at. If you are still completing your first thirty rated games, or you are a junior, tick the box that applies.
- 2
Add one row per game: the opponent’s rating, and whether you won, drew or lost.
- 3
Read the expected score beside each row; the number in brackets is the rating difference actually used after the cap.
- 4
The panel shows your new rating, the change, and the event’s performance rating.
Frequently asked questions
- How does FIDE calculate a rating change?
- For each game it takes the rating difference, reads the expected score from table 8.1.2, and subtracts it from what you actually scored. Those differences are added up across the event and multiplied by your development coefficient K. The result is rounded to a whole number, with a half rounding away from zero.
- What K-factor applies to me?
- K is 40 while you are completing events totalling your first 30 rated games, and 40 for a player until the end of the year of their 18th birthday as long as their rating is under 2300. It is 10 once a published rating has reached 2400, and stays there even if the rating later drops. Otherwise it is 20.
- Why is the difference capped at 400 points?
- To stop a single result against a far weaker or far stronger opponent from moving a rating too far. Since 1 October 2025 the cap only applies to players rated below 2650; from 2650 up the true difference is used in every case.
- Does this work for rapid and blitz ratings?
- Yes. The rapid and blitz regulations use the same probability table and the same K rules as the standard list, so the arithmetic here applies to all three. What differs is which events count towards which list.
- Is this an official FIDE tool?
- No. It implements the published FIDE Rating Regulations, but the rating list itself is the authority. Your federation may also rate the same event on a national list with different rules.
- Where do I get my opponents’ ratings from?
- The pairing sheet or the tournament’s published start list carries them, and they are the ratings used for the calculation, not whatever the opponent is rated by the time the list is published.
The scoresheets from that event are still in your bag
ScanChess turns a photographed scoresheet into a validated PGN, so the games behind the rating change are searchable instead of stacked in a drawer.
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