Buchholz

Buchholz (BH) is a tie-break designed for Swiss tournaments, where opponents are paired round by round and not everyone plays everyone else. It is meant to reflect how difficult a player's schedule was. At the end of the tournament, take the final score of every opponent the player faced and add those scores together. If two players finish on the same score, a higher Buchholz usually means one faced opponents who, as a group, performed better.

For example, if a player's opponents finish with 6, 5, 4, 4, and 3 points, the raw Buchholz is 22. The player's result against each opponent does not change that sum: beating or losing to the opponent with 6 points does not change that opponent's 6-point contribution. This distinguishes Buchholz from Sonneborn-Berger, which weights an opponent's score by the result achieved against that opponent.

Current rules of the International Chess Federation (FIDE) say Buchholz must not be used in round-robin events, where participants essentially share the same opponent field. Unplayed rounds also receive special adjustments for tie-break calculation. Buchholz Median-1 is a variation that removes one low and one high contribution.