Each team has eleven players on the field, and the rulebook decides more about them than you would expect: which numbers they are allowed to wear, whether they may legally catch the ball, and how many of them must be on the line when the play begins.
The trick that trips up newcomers is that the eleven who attack are entirely different people from the eleven who defend. They swap on and off as the ball changes hands, so you are really watching two separate teams take turns.
What each of those players actually does, the quarterback’s job, how a receiver runs a route, why a linebacker drops into coverage, is a bigger subject than the rules alone. I have pulled both squads apart in how the offense works and how the defense works. This page stays on the rules that govern them.
Eleven a side, and no more
The eleven is not a convention. It is a rule, with a penalty attached.
NFL rulebook, Rule 5, Section 1. Penalty: For more than 11 players in the formation prior to the snap or free kick: Loss of five yards from the succeeding spot.
Teams get caught by this more often than you would think, and almost always for the same reason. Because the offense and the defense are different people, every change of possession means eleven players run off and eleven run on. A substitution that is a fraction too slow, or a twelfth man who hesitates on his way to the sideline, is five yards before a ball has been snapped.
The numbers on the shirts are a rule, not a style choice
A player cannot pick whatever number he likes. The rulebook assigns ranges by position.
NFL rulebook, Rule 5, Section 1, Article 2 (Players Numbered by Position). Such numerals must be by playing position, as follows: (a) quarterbacks: 0-19; (b) punters and placekickers: 0-49 and 90-99; (c) defensive backs: 0-49; (d) running backs, fullbacks, tight ends, H-backs, and wide receivers: 0-49 and 80-89; (e) offensive linemen: 50-79; (f) defensive linemen: 50-79 and 90-99; (g) linebackers: 0-59 and 90-99.
| Position | Allowed numbers |
|---|---|
| Quarterbacks | 0-19 |
| Punters and placekickers | 0-49, 90-99 |
| Running backs, fullbacks, tight ends, wide receivers | 0-49, 80-89 |
| Offensive linemen | 50-79 |
| Defensive linemen | 50-79, 90-99 |
| Linebackers | 0-59, 90-99 |
| Defensive backs | 0-49 |
So the number is a label. Spot a 6 and you are almost certainly looking at a quarterback or a kicker. Spot a 74 and you are looking at a lineman. It is the quickest read available to a newcomer, and it works before you know a single player’s name.
One word to watch while you are reading numbers. That word again: a safety here is a defensive player, one of the deepest defenders on the field, and nothing to do with the two-point score of the same name.
Who is allowed to catch a pass
Here is where the numbers stop being trivia. The rulebook ties them to who may legally catch the ball.
NFL rulebook, Rule 5, Section 1, Article 2. Eligible pass receivers and a T-formation quarterback must be wearing numerals 0-49 or 80-89. All other numerals are worn by ineligible players unless they report a change in their position.
Which is why the five men in the fifties, sixties and seventies never catch anything. They are not merely bad at it. They are not allowed. An offensive lineman who catches a forward pass has committed a penalty, not made a play.
And those five are the reason the rest of it works. Games are won and lost by the five linemen who never touch it. They block for the quarterback, they open the gaps a runner goes through, and they are judged almost entirely on things that do not appear in any highlight. Start watching the line instead of the ball for one drive and the sport changes shape. The men who make an offense work are the ones nobody names on the walk home.
The left tackle is consistently among the best paid positions in the sport, usually second only to the quarterback, which tells you what teams privately think protection is worth.
Seven of them have to be on the line
One more rule shapes what you are looking at before every snap.
NFL rulebook, Rule 7, Section 5, Article 1 (Position of Players at the Snap). The offensive team must comply with the following at the snap: (a) It must have seven or more players on the line… (b) Eligible receivers must be on both ends of the line, and all of the players on the line between them must be ineligible receivers.
That is the shape on every play: seven or more men in a row, the ones on each end allowed to catch, everyone sandwiched between them not. Get it wrong and it is an illegal formation.
It also explains something you will see and wonder about. Occasionally a lineman trots over to tell the referee something before a play. He is reporting as eligible, which the numbering rule allows, and for that one play a man in the fifties can legally catch the ball.
Special teams, the third unit
Beyond the offense and the defence there is a third group who come on only for kicking plays: the kicker, the punter, the long snapper who fires the ball back to them, and the returner who catches it at the other end.
They are on the field for the fewest snaps of anyone and they decide a startling share of close games, because field position and three points at a time add up.
Common questions
How many players are on the field in American football?
Eleven from each team, so twenty-two in total. The eleven who attack and the eleven who defend are different players, and they swap on and off as possession changes. More than eleven in the formation is a five-yard penalty.
What do the numbers on NFL jerseys mean?
They are set by rule, not by choice. The rulebook assigns number ranges by position: quarterbacks wear 0-19, offensive linemen 50-79, linebackers 0-59 and 90-99, and so on. The number tells you what job a player does before you know his name.
Who is allowed to catch a pass in the NFL?
Only eligible receivers, and the rulebook ties eligibility to the shirt number: a player must be wearing 0-49 or 80-89 to be an eligible pass receiver. That is why offensive linemen, wearing 50-79, never catch the ball. A lineman can report as eligible to an official before a play, which is the exception you occasionally see.
Where to go next
- How the offense works: what each attacking player actually does
- How the defense works: the three layers and how they fit together
- NFL downs explained: the four-downs cycle everyone on the field is working towards
- NFL rules decoded: how the whole game fits together
- Penalties and pass interference decoded: the fouls each position tends to commit
Numbering is Rule 5 and formation is Rule 7 of the official NFL rulebook, published by NFL Football Operations.