A number that estimates a player's strength relative to others in the same pool, based on their results. The gap between two ratings predicts the expected score between them, and ratings move after each game by K × (actual − expected). It was created by Arpad Elo and adopted by the US Chess Federation in 1960 and FIDE in 1970.[1]
How is Elo calculated?
Expected score E = 1 / (1 + 10^((opponent − you) / 400)). New rating = old rating + K × (S − E), where S is 1 for a win, 0.5 for a draw and 0 for a loss. Try it in the Elo calculator.[2]
What does a 100, 200 or 400-point rating difference mean?
With the standard formula, the higher-rated player's expected score is about 64% at 100 points, 76% at 200 and 91% at 400 (10 to 1 odds). FIDE describes 200 points as about 75%. See the full table.[4]
What K-factor does FIDE use?
K = 40 for new players until they have completed 30 games, and for juniors until the end of the year they turn 18 while they're rated under 2300. K = 20 while a rating stays under 2400. K = 10 once a published rating has reached 2400. If K × games in a period would exceed 700, K is reduced so it doesn't.[3]
What K-factor should I use for my own league?
Most casual leagues use 20–40. A higher K reacts faster but is noisier. Our K-factor guide compares the values used by FIDE, US Chess, FIFA and FiveThirtyEight.
What is a good Elo rating?
It depends entirely on the pool, so there's no universal answer. Ratings are relative to the players in the same system. Lichess points out that ratings from different organisations can't be compared.[5]
Why is my Chess.com rating different from my Lichess or FIDE rating?
They use different systems: Glicko on Chess.com, Glicko-2 on Lichess and Elo at FIDE. They also have different starting points and different player pools. See Chess.com vs Lichess vs FIDE.[6][5][3]
Can I lose rating points after a draw?
Yes, if you're the higher-rated player. Your expected score was above 0.5, so a draw is below expectation. The lower-rated player gains the same amount when both use the same K.
What is the lowest FIDE rating?
FIDE publishes ratings of 1400 and above. Players whose rating drops below 1400 are shown as unrated on the next list.[3]
What is the difference between Elo and Glicko?
Glicko adds a rating deviation (RD) that measures how reliable a rating is. RD shrinks as you play and grows when you're inactive, so uncertain ratings move faster. Glicko-2 also adds volatility. See Elo vs Glicko-2 vs TrueSkill.[7]
How is a tournament performance rating calculated?
FIDE's method is Rp = Ra + dp: the average opponent rating plus a rating difference read from a table based on your score percentage. Use the performance rating calculator.
Is the league tool free, and where is my data stored?
Yes, it's free with no sign-up. League data is stored in your browser's local storage on your device. Share links carry the league data after the "#" in the address, which browsers don't send to our server. See the privacy page.