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Chess Rating Calculator

Work out your expected score and rating change against any opponent, for a win, draw or loss.

Written by Jude Ramsey · Last updated August 2026 · How these calculators are checked

What this calculator does

The Elo system converts a rating gap into an expected score. Every 400 points of advantage means the stronger player is expected to score ten times as often as the weaker one, and rating changes are simply the difference between the result and that expectation.

The K-factor sets how fast ratings move. New players use a high K so their rating finds its level quickly; established masters use a low one so a single result does not swing them far.

How to fill it in

  1. Enter your rating and your opponent’s.
  2. Choose the K-factor your federation or site uses.
  3. Pick the result to see the rating change.

Formula reference

expected score E = 1 ÷ (1 + 10^((opponent − you) ÷ 400)) new rating = old rating + K × (actual score − expected score)

Try it with these numbers

The calculator opens with a games in a series of 1. On those figures the new rating is 1,514. Underneath, Expected score comes out at 29.66% and Rating change at +14.1. Change any field and every figure updates as you type.

Common questions

What is a K-factor?
A multiplier controlling how much a single game moves your rating. FIDE uses 40 for new players, 20 for most, and 10 above 2400.
Why does a draw sometimes lose me points?
Because if you were expected to score more than half against a weaker opponent, a draw is a worse result than expected.
Does beating a much weaker player help?
Barely. If you were expected to score 0.97, winning gains you only three percent of the K-factor.

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