The maximum number of rounds in a professional boxing championship match is 12.
Modern professional championship bouts are normally scheduled for twelve rounds, with each men's round lasting three minutes and a one-minute rest between rounds. A full contest therefore contains 36 minutes of fighting, spread across 47 minutes including the intervals.
The twelve-round limit replaced the older fifteen-round championship format. The change followed the 1982 death of South Korean boxer Kim Duk-koo after his WBA lightweight title fight with Ray Mancini. Medical concerns about the dangers of prolonged fights helped drive the World Boxing Council to adopt twelve rounds for championship contests in 1983, and the format became standard across major professional boxing.
Not every professional bout lasts twelve rounds. Preliminary and non-title fights may be scheduled for four, six, eight, or ten rounds, depending on the boxers' experience and the event's importance. A fight can also end early by knockout, technical knockout, disqualification, or the judges' decision after an interruption.