Elo Rating Calculator
Calculate win probability and new ratings after a match using the Elo rating system.
Last reviewed: April 2026About the Elo Rating Calculator
Elo ratings are a system used to rate the skill level of players in games such as chess, Go, and other two-player games. The system was developed by Hungarian chess grandmaster Arpad Elo in the 1950s. The Elo rating system is widely used in many sports and video games to determine the relative skill levels of players.
The Elo rating is a numerical value that represents a player's skill level. A player's rating is updated after each game based on the outcome of the match and the ratings of the opponents. The formula used to calculate the new rating is based on the difference in ratings between the two players and the result of the game. The more a player's rating changes, the more significant the impact of the game result.
The Elo rating system is designed to be a self-correcting system. As players' skill levels change over time, their ratings will adjust accordingly. This means that a player's rating isn't a fixed value and can change with each game played.
Real-World Applications
The Elo rating system has many real-world applications beyond just chess and other games. In the business world, the Elo rating system is used to rank companies based on their financial performance. In the entertainment industry, the Elo rating system is used to rank movies and TV shows based on their popularity and ratings.
In sports, the Elo rating system is used to rank teams and players based on their performance. For example, the Elo rating system is used to rank NFL teams based on their performance in the regular season. The system is also used to rank individual players based on their performance in games and tournaments.
Common Mistakes
One common mistake when using the Elo rating system is assuming that a player's rating is a fixed value. As mentioned earlier, a player's rating isn't a fixed value and can change with each game played. that a player's rating is a reflection of their current skill level and can change over time.
Another common mistake is assuming that a player's rating is a measure of their overall ability. While the Elo rating system is a useful tool for comparing players, it isn't a measure of a player's overall ability. A player's rating is a reflection of their performance in a specific game or set of games and may not accurately reflect their overall ability.
Examples
Let's consider an example of how the Elo rating system works. Suppose two players, Player A and Player B, are playing a game. Player A has a rating of 1500 and Player B has a rating of 1400. The difference in ratings between the two players is 100 points. If Player A wins the game, Player A's rating will increase and Player B's rating will decrease. The amount by which the ratings change will depend on the outcome of the game and the ratings of the players.
Now, let's consider a counterexample. Suppose two players, Player A and Player B, are playing a game. Player A has a rating of 1500 and Player B has a rating of 1600. The difference in ratings between the two players is -100 points. If Player A wins the game, Player A's rating will decrease and Player B's rating will increase. The amount by which the ratings change will depend on the outcome of the game and the ratings of the players.
What happens if Player A and Player B have the same rating? If Player A wins the game, Player A's rating will increase and Player B's rating will decrease. The amount by which the ratings change will depend on the outcome of the game and the ratings of the players.