How to use the Elo calculator
- Enter your current rating and the K-factor your rating system uses. If you're not sure, FIDE uses 20 for most adult players.
- Add each opponent's rating and choose your result: W for a win (1 point), D for a draw (½ point) or L for a loss (0 points).
- Read your new rating. The calculator adds up your expected score across every game, compares it with your actual score and applies the K-factor.
You can change a result or remove a game at any time, and the totals update immediately. Your games are stored in your browser only, so they're still there when you come back after the next round.
What is the Elo rating system?
The Elo rating system measures the relative strength of players in two-player games. It was developed by Hungarian-American physicist and chess master Arpad Elo, adopted by the US Chess Federation in 1960 and by FIDE, the international chess federation, in 1970.
Each player's rating is a prediction. When two players meet, the difference between their ratings gives an expected score for each of them. After the game, the winner takes points from the loser. How many depends on how surprising the result was: beating a much stronger player earns a lot, and beating a much weaker one earns very little.
Elo's approach is also used, often with changes, in table tennis, Go, Scrabble, football and esports rankings, and in matchmaking for many online games.
The Elo rating formula
The calculation has two steps. First, the expected score against an opponent:
Then the new rating, using your actual score S (1 for a win, 0.5 for a draw, 0 for a loss) and the K-factor:
For a tournament, add up your expected scores from every game and compare the total with your total score. The calculator above does this, which matches how FIDE calculates rating changes for a rating period.
The 400-point rule
FIDE's rating regulations treat any rating difference greater than 400 points as exactly 400. This means a player can still lose a few points to a much weaker opponent. Tick Apply FIDE 400-point rule in the calculator to use it.
Expected score by rating difference
The expected score is the share of points a player should average against an opponent. It includes draws, so it isn't strictly a win probability, but it's often described as one.
| Rating difference | Stronger player | Weaker player |
|---|---|---|
| 0 | 50% | 50% |
| 50 | 57% | 43% |
| 100 | 64% | 36% |
| 150 | 70% | 30% |
| 200 | 76% | 24% |
| 300 | 85% | 15% |
| 400 | 91% | 9% |
| 600 | 97% | 3% |
| 800 | 99% | 1% |
What is the K-factor?
The K-factor is the maximum number of points a single game can move your rating. A high K lets a rating catch up quickly with a player's real strength. A low K keeps established ratings stable.
| K | Who it applies to (FIDE) |
|---|---|
| 40 | New players until they've completed 30 rated games, and players under 18 while rated below 2300 |
| 20 | Players rated below 2400 |
| 10 | Players who have reached 2400. K stays at 10 after that, even if the rating drops |
National federations, clubs and online platforms often use their own values. K = 32 is a common choice for club ladders and casual systems. Check your organisation's rules for the exact figure.
Worked example
You're rated 1600 and you play someone rated 1800, with K = 20.
1. Expected score
You're expected to score about 24% against this opponent.
2. Rating change
| Result | Calculation | New rating |
|---|---|---|
| Win | 1600 + 20 × (1 − 0.24) | 1615.2 (+15.2) |
| Draw | 1600 + 20 × (0.5 − 0.24) | 1605.2 (+5.2) |
| Loss | 1600 + 20 × (0 − 0.24) | 1595.2 (−4.8) |
Beating the stronger player earns three times what losing to them costs. Even a draw gains points, because you scored more than expected.
What does an Elo rating mean?
Ratings only make sense next to others in the same pool, but in FIDE-rated chess these are rough guidelines:
| Rating | Typical level |
|---|---|
| 1400–1800 | Club player |
| 1800–2000 | Strong club player |
| 2000–2200 | Expert / candidate master |
| 2300+ | FIDE Master (FM) title threshold |
| 2400+ | International Master (IM) threshold, plus norms |
| 2500+ | Grandmaster (GM) threshold, plus norms |
| 2700+ | World elite ("super-GM") |
Elo outside over-the-board chess
Chess.com uses the Glicko rating system and Lichess uses Glicko-2. Both are related to Elo but also track how reliable each rating is, so results from this calculator are only approximate for those sites. Most competitive video games use Elo-inspired matchmaking ratings (MMR) with formulas they don't publish.
Playing timed games? A chess clock helps you practise time management for blitz, rapid and classical play.
Frequently asked questions
How is an Elo rating calculated?
Your new rating equals your current rating plus K × (actual score − expected score). The expected score against one opponent is 1 / (1 + 10(opponent − you) / 400). Wins count as 1, draws as 0.5 and losses as 0.
What K-factor should I use?
FIDE uses K = 40 for new players (fewer than 30 rated games) and for juniors under 18 rated below 2300, K = 20 for players rated below 2400, and K = 10 for players who have reached 2400. Other organisations use their own values, so check the rules of your rating system.
How many points do I gain for beating a higher-rated player?
It depends on the rating gap and the K-factor. With K = 20, beating a player rated 200 points above you earns about +15, while losing to them costs only about −5. The bigger the upset, the more points you gain.
Is this calculator accurate for Chess.com or Lichess ratings?
Only approximately. Chess.com uses the Glicko system and Lichess uses Glicko-2, which also track how certain each rating is. This calculator uses the classic Elo formula used by FIDE and many national federations.
What is the FIDE 400-point rule?
Under FIDE rating regulations, a rating difference of more than 400 points is treated as exactly 400 points when calculating the expected score. You can switch this rule on in the calculator.
Is there an Elo calculator app for iPhone?
Yes. Elo Calculator - Chess Rating is a free iPhone app on the App Store. It lets you keep a ladder of your club's players and save as many opponents as you like on your phone.