Uniform number (American football)

Cornerback Dré Bly seen in 2007 with numbers visible on the front and shoulders of his uniform

In American football, uniform numbers are displayed on both the front and back of the jersey, and in many cases the sleeves, shoulder pad, or occasionally helmets. The numbers on the front and back are very large, covering most of the jersey. Certain numbers may only be worn by players in specific positions, thus assisting the officials in determining penalties.

At all levels of football, each player dressed for a game must wear a unique number from 0 to 99. The number 0, long prohibited in American football, has been permitted in college football since 2020 and in the National Football League since the 2023 season.

Players who wear numbers from 50 to 79 are, by rule, prohibited from catching or touching forward passes if their team is in possession of the ball and may not line up in a position that allows them to do so, unless explicitly indicated to the referee during a tackle-eligible play. Other than this, the correspondence between jersey numbers and player positions is largely a matter of style, tradition and semantics.

Canadian football follows a similar numbering scheme to that of American football, except that the ineligible numbers span only 50 to 69 and numbers 0 and 00 have long been available for use, although beginning in the 2023 CFL season a Canadian Football League team is not permitted to simultaneously issue both. 00 remains prohibited in American football.