Elo Rating Calculator

See how a chess or game result changes each player's Elo rating.

Your rating	1,500
Opponent's rating	1,650
Result	Win
K-factor	20

Your rating

Opponent's rating

Result

K-factor

FIDE: 40 for new players and under-18s below 2300, 20 below 2400, 10 at 2400+.

New rating

1,514.1

Change +14.1. Your expected score was 0.297 (about 30% of the points); opponent changes by -14.1.

Expected score against the rating gap (your rating − opponent's)

You: 30% expectedat (-150, 0.296615)Point at the chart, or Tab to it and use ← →

You: 30% expected: (-150, 0.3)

About the Elo Rating Calculator

Enter both players' ratings, the result (win, draw or loss) and the K-factor. The calculator gives your expected score, your new rating and the change for both players.

The Elo system predicts each player's expected score from the rating difference: a 200-point edge gives about a 76% expected score. After the game, ratings move by K × (actual − expected). FIDE uses K = 40, 20 or 10 depending on experience and rating.

The formula

E = 1 ÷ (1 + 10^((Rb − Ra) ÷ 400)); R′ = R + K (S − E)

Worked example

A 1500 player beats a 1650 player, K = 20

Expected score: 1 ÷ (1 + 10^(150 ÷ 400)) = 0.297
Change: 20 × (1 − 0.297) = +14.1
New rating 1514.1; the opponent drops 14.1

Questions people ask

Does a draw change ratings?

Yes: the lower-rated player gains if they draw.

Is FIDE exactly this?

FIDE also caps rating differences at 400 for calculation and rounds per its rules.

Sources

FIDE Rating Regulations