A 400-point rating gap means the stronger player is expected to score about 91%.
How to use the Elo Rating Calculator
- Your rating
- Opponent rating
- Result
- K-factor
Results update as you type, and every field accepts the units shown in its menu.
How it works
The expected score comes from the rating difference; the rating moves by K times the surprise.
Inputs explained
| Field | What to enter |
|---|---|
| Your rating | A number |
| Opponent rating | A number |
| Result | Choose one: Win, Draw, Loss |
| K-factor | A number |
What each result means
- Expected score = 1÷(1 + 10^(([Opponent rating] – [Your rating])÷400))
- New rating = [Your rating] + [K-factor]×([Result] – [Expected score])
- Change = [K-factor]×([Result] – [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 | 820 |
| 1,200 | 1,219 |
| 1,600 | 1,613 |
| 2,000 | 2,003 |
| 2,400 | 2,400 |
| 3,200 | 3,200 |
Formula
Expected = 1 ÷ (1 + 10^((R_b − R_a) ÷ 400))New rating = R_a + K × (score − expected)Worked example
Inputs — Your rating: 1,600; Opponent rating: 1,700; Result: Win; K-factor: 20.
Results — Expected score = 0.36; New rating = 1,613; Change = 12.8.
Frequently asked questions
What K-factor should I use?
FIDE uses 40 for new players, 20 for most players and 10 for players above 2400.
Why does beating a stronger player give more points?
Your result exceeded expectations by more.
What formula does the Elo Rating Calculator use?
Expected = 1 ÷ (1 + 10^((R_b − R_a) ÷ 400)).