Elo Rating Calculator
Work out your new Elo rating after a win, draw, or loss, with the expected score and the points you gained or lost.
How it works
Elo is the rating system chess borrowed and half the gaming world now uses. The idea is simple: before a game, your rating and your opponent's predict how likely each of you is to win. Beat someone stronger and you jump a lot; beat someone much weaker and you barely move.
The expected score comes from the 400-point rule — every 400 points of rating gap roughly means a tenfold difference in odds. Your new rating is your old one plus the K-factor times the gap between how you actually did and how you were expected to do.
The K-factor controls how twitchy the system is. A high K like 40 swings ratings fast, good for newcomers still finding their level; a low K like 10 barely nudges established players. Enter your numbers and pick a result to see exactly where you land.
Frequently asked questions
How is the new rating calculated?
New rating equals your current rating plus K times the difference between your actual score and your expected score. A win counts as 1, a draw as 0.5, and a loss as 0. For two 1500 players with K=32, a win gives 1500 + 32 × (1 − 0.5) = 1516.
What K-factor should I use?
Chess federations often use 40 for new players, 20 for most, and 10 for masters. Higher K means your rating reacts faster to results. If you're not sure, 32 is a common all-purpose choice used by many online sites.
What does the expected score mean?
It's your predicted chance of winning, from 0 to 1, based only on the rating gap. Equal ratings give 0.5, meaning a coin flip. The bigger your rating lead, the closer the expected score creeps toward 1.