Quarterbacks and specialists, like kickers can choose from a number between 1 and 19. Running backs and defensive backs all have the options of 20-49. Centers and linebackers can choose between 50-59. Linemen on both sides of the ball wear 60-79. Wide receivers and tight ends share the numbers from 80-89. Defensive linemen and linebackers can also choose from 90-99.

The other restriction on numbers, are those which are retired by respective teams. In the 49ers case, that means numbers 34, 12, 39, 37, 73, 70, 87, 16 and 79 are all off limits. These numbers belong to (in order) Joe Perry, John Brodie, Hugh McElhenny, Jimmy Johnson, Leo Noemilini, Charlie Krueger, Dwight Clark, Joe Montana and Bob St. Clair.

It’s easy to see how numbers can be exhausted quickly. Considering the 49ers are likely to retire the number of Jerry Rice, that will leave only eight numbers for their receivers. The team has way more than that over the course of an off-season, and usually carries between four and five on the roster.

Last season Vinny Sutherland wore number twenty-five, but was on the roster as a receiver. Not wanting to change his number, Sutherland asked for his position to be changed officially to running back. It made little difference to the team that used Sutherland primarily as a kick returner. Suitherland was not afforded the same luxury as Keyshawn Johnson of the Jets/Buccaneers who plays receiver and wears number 19. Johnson was granted special permission by the NFL to wear his college number because when joining his first NFL active roster, there were no numbers in the 80s available to him. He has since kept that number.

There is of course one double digit number that is considered ineligible. The number 00 is generally reserved for team mascots and special events. For example if a person is to be honored at a game, they are generally given the 00 number.