How to Use the Chess Elo Rating Calculator
Enter your rating, your opponent's rating, the game result, and your K-factor to instantly see how much your Elo rating will change. The calculator follows the official FIDE Elo formula.
How Elo Works
The Elo system first computes the expected score — your probability of winning based on the rating difference. The actual result (win=1, draw=0.5, loss=0) minus the expected score, multiplied by K, gives the rating change. Surprising upsets produce larger swings; expected wins produce smaller ones.
Choosing Your K-Factor
FIDE uses K=40 for new players (under 30 rated games) and players under 18 below 2300. K=20 for most established players. K=10 for players rated 2400+ who have been on the list for at least 18 months. Online platforms (Chess.com, Lichess) use their own K-factor systems.
FAQ
FIDE ratings have a floor of 1000. Online platforms set their own minimums and may use different floor rules.
It uses the standard FIDE formula but does not account for bonus points or special tournament regulations. Use it as a reference only.
Because your expected score is very high, the difference between expected and actual is small — meaning a smaller K multiplier and less rating gain.