How Does the Elo Rating System Work?
Every competitive chess player has an Elo rating, a number that represents their strength. Named after physicist Arpad Elo, the system has been used by FIDE since 1970. Here is exactly how it works.
The basic idea
The Elo system assigns each player a numerical rating. When you win, your rating goes up. When you lose, it goes down. The key insight: the amount of change depends on the strength of your opponent. Beating a much higher-rated player gives you more points than beating a lower-rated one.
The maths
The expected score is calculated using the formula: E = 1 / (1 + 10(Ropponent-Ryou)/400). If your rating is 1500 and your opponent is 1700, your expected score is about 0.24 (24% chance of winning). After the game, your new rating = old rating + K × (actual score - expected score), where K is typically 20-40.
What ratings mean
Approximate rating levels:
| Rating | Level |
|---|---|
| 0-1000 | Beginner |
| 1000-1400 | Casual player |
| 1400-1800 | Club player |
| 1800-2000 | Strong club player |
| 2000-2200 | Expert/Candidate Master |
| 2200-2400 | FIDE Master (FM) |
| 2400-2500 | International Master (IM) |
| 2500+ | Grandmaster (GM) |
| 2800+ | World elite |