Elo Rating Calculator
Calculate Elo rating changes for chess, sports, and competitive games
Calculate Elo Rating Change
Current category: Class C
Higher K-factors mean larger rating changes
Rating Change Results
Formula used: Rating Change = K × (Actual Score - Expected Score)
Expected Score: 1 / (1 + 10^((Opponent Rating - Your Rating) / 400))
K-Factor: 40 (auto-adjusted)
Rating Analysis
Example Calculation
Chess Tournament Example
Your rating: 1750
Opponent rating: 1810
Result: You won the game
K-factor: 20 (club player level)
Step-by-Step Calculation
1. Rating difference: 1810 - 1750 = 60
2. Expected score: 1 / (1 + 10^(60/400)) = 0.414
3. Actual score: 1 (win)
4. Rating change: 20 × (1 - 0.414) = +11.7
New rating: 1750 + 11.7 = 1761.7
Rating Categories (Chess)
K-Factor Guidelines
40 - Beginners
Rapid rating changes for new players
20 - Club Players
Standard K-factor for most players
15 - Strong Players
For players rated above 2300
10 - Masters
Stable ratings for top players (2400+)
Elo Rating Tips
400-point difference = 10x more likely to win
Rating changes are symmetric (win = opponent loss)
Higher K-factors mean more volatile ratings
System works best with large player pools
Beating higher-rated opponents gives more points
Understanding the Elo Rating System
What is the Elo Rating System?
The Elo rating system is a method for calculating the relative skill levels of players in zero-sum games such as chess, Go, and many sports. It was originally developed by Hungarian-American physics professor Arpad Elo for chess ratings.
Key Principles
- •Higher-rated players are expected to score higher against lower-rated opponents
- •Rating changes are based on the difference between expected and actual results
- •The system is zero-sum: one player's gain equals the opponent's loss
Mathematical Formula
Expected Score = 1 / (1 + 10^((Rb - Ra) / 400))
New Rating = Old Rating + K × (Score - Expected Score)
Applications
- •Chess: FIDE uses modified Elo for official ratings
- •Sports: NBA, FIFA, tennis rankings
- •Gaming: Online games like League of Legends, CS:GO
- •Other Games: Scrabble, Go, poker tournaments