About the FIDE Rating Regulations
This calculator implements the official FIDE Rating Regulations (effective March 2024), the primary document governing K-factors, expected score, and initial rating. Two amendments extend those rules: the 2650+ Classical exception (October 2025) and the faster time-control inclusion (January 2026).
The 2650+ Classical Exception
A FIDE Council amendment effective October 2025 removed the 400-point rating difference cap for Classical games involving a player rated 2650 or above. Previously, the cap prevented extreme rating gaps from being fully reflected in Elo calculations; the amendment ensures elite results are counted at full weight.
Faster Time Controls Now Count
A January 2026 resolution allows certain events with time controls such as 45 minutes + 30 seconds increment to be rated as standard Classical chess, provided they meet FIDE's criteria for major events. This calculator applies Classical rating rules to all games you enter.
How Elo Change is Calculated
Expected score: E = 1 / (1 + 10(opponent − player) / 400). Rating change: Δ = K × (result − E), where result is 1 for a win, 0.5 for a draw, 0 for a loss. The K-factor controls how much a single result can move your rating.
FIDE vs CFC Rating Systems
The FIDE system uses the continuous formula above. The CFC (Canadian Chess Federation) system uses an official 51-band lookup table instead, applies bonus points for exceptional tournament performance, and has a single rating list with no time-control variants.