Chess Elo rating calculator
Enter both ratings and the result to get the new Elo, the points gained or lost and the expected score — using the same formula FIDE applies. It works for chess, xiangqi or any rating pool built on the Elo scale.
A bigger K moves your rating faster. FIDE uses 40 for players with fewer than 30 rated games, 20 for players who have never reached 2400, and 10 once a player has been 2400 or above.
The Elo formula
Your expected score is E = 1 / (1 + 10 ^ ((opponent rating − your rating) / 400)). A 400-point gap means the stronger player is expected to score about ten wins out of eleven.
New rating = old rating + K × (S − E), where S is the actual result: 1 for a win, 0.5 for a draw, 0 for a loss. In other words you only gain points by doing better than the system expected of you.
Which K-factor applies
- K = 40 — a new player with fewer than 30 rated games, or a player under 18 rated below 2300.
- K = 20 — a player past 30 games who has never reached 2400.
- K = 10 — a player who has reached 2400 at any point, even if they are now below it.
- Online sites commonly use anything from 10 to 32 depending on the time control, which is why your rating there rarely matches your FIDE number.
Why beating a weaker player earns so little
Because the system already expected it. Three hundred points ahead puts E around 0.85: a win earns K × 0.15, while a loss costs K × 0.85. The wider the gap, the more the risk sits with the favourite.
That is also why the fastest way up is to play opponents at or above your level rather than picking easy games.
Chesslizar ratings work slightly differently
The Chesslizar ladder uses Glicko rather than plain Elo: alongside the number there is a rating deviation that says how sure the system is about you. New or returning players have a high deviation and move faster; regular players settle down.
This calculator implements classical Elo, so treat the result as an estimate for FIDE and other Elo pools rather than the exact number the Chesslizar leaderboard will show.
Frequently asked questions
Do you gain rating for drawing a stronger player?
Yes. If your expected score is below 0.5, a draw is better than expected, S − E is positive, and your rating goes up.
What rating does a beginner start at?
FIDE issues a first rating once you have played enough games against rated opponents. Online sites usually start players between 1000 and 1500; Chesslizar starts at 1000.
Do both players always exchange the same number of points?
Only when both use the same K-factor. If they differ — a newcomer facing a titled player — the one with the larger K moves further.
Does the same formula work for xiangqi?
Yes. The Elo formula does not care which game is being played; only the K-factor and the starting rating differ between federations.