Elo Calculator
Enter two Elo ratings, the match result, and a K-factor to see how each player’s or team’s rating changes after the game.
What is an Elo rating?
The Elo rating system, created by Arpad Elo, is a method for calculating the relative skill levels of players or teams in competitive games such as chess, esports, and many sports leagues. Every player has a numeric rating that rises after wins and falls after losses, with the size of the change depending on how surprising the result was.
How the calculation works
Each player’s expected score against the other is calculated from the rating difference using the logistic formula 1 / (1 + 10^((opponent rating – own rating) / 400)). After the match, the new rating is the old rating plus the K-factor multiplied by the difference between the actual score (1 for a win, 0.5 for a draw, 0 for a loss) and the expected score.
The K-factor controls how much a single result can move a rating – higher K-factors (like 32) are common for casual or lower-level play, while lower K-factors (like 10-16) are typical for elite or well-established players where ratings should move more slowly.
This tool is for general reference and game analysis purposes; specific leagues or platforms may use slightly different K-factor rules or rating floors.