Arpad Elo’s rating system ranks chess players, and now everything from football clubs to video-game players. Beating a stronger opponent earns more points than beating a weaker one. K sets how fast ratings move.
How to use the Elo Rating Calculator
- Your rating
- K-factor
- Game 1 opponent rating
- Game 1 result
- Game 2 opponent rating
- Game 2 result
- Game 3 opponent rating
- Game 3 result
- Game 4 opponent rating
- Game 4 result
- Game 5 opponent rating
- Game 5 result
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter your rating, the K-factor (FIDE uses 40 for new players, 20 normally and 10 for top players), and each opponent’s rating and result. Leave unused games’ opponent rating at 0.
Inputs explained
| Field | What to enter |
|---|---|
| Your rating | A number |
| K-factor | A number |
| Game 1 opponent rating | A number |
| Game 1 result | Choose one: Win, Draw, Loss |
| Game 2 opponent rating | A number |
| Game 2 result | Choose one: Win, Draw, Loss |
| Game 3 opponent rating | A number |
| Game 3 result | Choose one: Win, Draw, Loss |
| Game 4 opponent rating | A number |
| Game 4 result | Choose one: Win, Draw, Loss |
| Game 5 opponent rating | A number |
| Game 5 result | Choose one: Win, Draw, Loss |
What each result means
- Expected score = [e1] + [e2] + [e3] + [e4] + [e5]
- Rating change = [K-factor]×([Actual score] – [Expected score])
- New rating = [Your rating] + [K-factor]×([Actual score] – [Expected score])
Example values
How the main result changes when Your rating changes and everything else stays at the example values above:
| Your rating | New rating |
|---|---|
| 800 | 829.6 |
| 1,200 | 1,226.6 |
| 1,600 | 1,611.4 |
| 2,000 | 1,994.4 |
| 2,400 | 2,390.5 |
| 3,200 | 3,190 |
Formula
E = 1 / (1 + 10^((R_opp − R)/400)), ΔR = K × Σ(S − E), R_new = R + ΔR
Worked example
Inputs: Your rating: 1,600; K-factor: 20; Game 1 opponent rating: 1,700; Game 1 result: Win; Game 2 opponent rating: 1,550; Game 2 result: Draw; Game 3 opponent rating: 0; Game 3 result: Loss; Game 4 opponent rating: 0; Game 4 result: Loss; Game 5 opponent rating: 0; Game 5 result: Loss.
Results: Expected score = 0.931; Actual score = 1.5; Rating change = 11.4; New rating = 1,611.4.
Key terms
- Expected score
- Probability-based expected result (1 = win).
Frequently asked questions
What K-factor should I use?
FIDE: 40 for new players, 20 for most, 10 for players above 2400.
What does a 400-point gap mean?
The stronger player is expected to score about 91%.
Does a draw change ratings?
Yes, if the players' ratings differ.
Is Elo used outside chess?
Yes, in football, esports and online games.