Free tool
Chess rating change estimator
How it works
Enter your rating, an opponent’s rating, and the result. The calculator computes your expected score from the Elo formula, 1 / (1 + 10^((opponent - you) / 400)), then shows the exact point change side by side at FIDE K = 40, 20, and 10, so you can see the range before you know your own K-factor.
Expected score
0.43
About 43% chance-equivalent against 1450
| K-factor | Who it applies to | Point change | New rating |
|---|---|---|---|
| K = 40 | New players; juniors under 18 rated below 2300 | +22.9 | 1423 |
| K = 20 | Established rating below 2400 | +11.4 | 1411 |
| K = 10 | Reached 2400 or higher | +5.7 | 1406 |
FIDE K-factors depend on age and rating history, not only current rating, so check the FIDE Handbook for which row applies before acting on it. Online platforms such as Lichess use a Glicko-based system instead of a fixed K-factor, which is why the same game moves an online rating by a different amount.
The method behind the numbers
Point change = K x (score - expected), where expected = 1 / (1 + 10^((opponent - you) / 400))
FIDE does not use one K-factor for everyone. K = 40 applies to new players and to juniors under 18 rated below 2300, K = 20 applies once a player has an established rating below 2400, and K = 10 applies after a player has reached 2400 or higher. The same result against the same opponent moves a rating by four times as many points at K = 40 as it does at K = 10.
Showing all three K-factors side by side is deliberate: a player rarely knows their exact bracket without checking the FIDE Handbook, and a coach estimating a student’s likely rating move often wants the full range rather than a single guess. Pick the row that matches the player’s actual category for the number that will apply.
Online ratings move differently. Lichess and similar platforms use a Glicko-based system that tracks a rating deviation, a measure of how uncertain the rating still is, and moves newer or more uncertain ratings faster than any fixed K-factor. That is why the same game changes a FIDE-style estimate and an online rating by different amounts.
Frequently asked questions
What is a K-factor and why does it matter?
The K-factor sets how many rating points are at stake in a single game: the point change is K times the difference between your actual score and your expected score. A bigger K means bigger swings in both directions, win or lose.
Why does this tool show three numbers instead of one?
Because your own K-factor depends on your rating history and, for juniors, your age, not just your current rating. Showing K = 40, 20, and 10 together lets you find the row that actually applies to you instead of assuming the wrong one.
Why is my Lichess or Chess.com rating change different from this estimate?
Those platforms use a Glicko-family system, not the fixed FIDE K-factor table. Glicko tracks a rating deviation per player and moves newer or more uncertain ratings faster, so the same result can change an online rating by a noticeably different amount than this FIDE-style estimate.
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