Free interactive tool
Elo Rating Calculator
Two ratings in, win probability out — plus what a win or loss would pay.
Price an upset before you play it
Set two ratings; the expected score and the rating swing follow the Elo formula.
Elo is a probability engine: 400 points means a 10:1 favorite, and the points exchanged after a game are exactly the surprise the result contained.
- Find the gap that makes you a 75% favorite.
- Why does beating a much higher rating pay so well?
Elo converts a rating gap into a win expectancy: E = 1 / (1 + 10^(Δ/400)). Four hundred points makes the stronger player a 10:1 favorite, and the points exchanged after a game equal exactly the surprise in the result.
Set your rating and an opponent's to price the matchup — and see why beating a higher-rated player pays so much better than grinding equals.
How many points for beating an equal opponent?
Half the K-factor — 16 points at K=32, since the result was a coin flip.
Is Elo only for chess?
No — the same math drives matchmaking in esports, table tennis, and most ranked ladders.