How many weight classes in the UFC?

Where the limits come from. They are set out in the Unified Rules of Mixed Martial Arts and are the UFC's own figures, not anything computed from our record. The pound figure is the rule; the kilogram figure is the conversion. A champion may weigh up to one pound over the limit at a title fight; everyone else may not. Where the dates come from. The first and last bout columns ARE computed — from 8,615 UFC bouts with a division on the official record. They are what the record shows, which is why a division whose title has been retired still has a last date rather than disappearing. 263 bouts sit in no division. Catchweights, open-weight bouts and the 1990s tournaments carry no weight class on the record, so they are counted in none of the rows above. They are not missing from our record — they are in the year-by-year archive like every other fight.