An Elo rating is a number that measures a chess player’s relative strength. The system was created by Arpad Elo and has been used by FIDE since 1970.
For every game, the system predicts the result from the rating gap. The basic formula: rating change = K × (score − expected score). Beating a stronger player earns a lot of points; losing to a weaker one costs a lot.
The lowest published FIDE rating is 1400. FIDE ratings are also the gateway to titles, such as 2300 for FIDE Master and 2500 for Grandmaster.
Chess.com and Lichess use a different system (Glicko), so their numbers cannot be compared directly with FIDE ratings.
Worked examples and how to get your first FIDE rating are in Elo Rating Explained.
Related terms: FIDE · Norm · Grandmaster
