Penalties in football are either 5, 10, or 15 yards, and sometimes just "spot of the foul". When the yardage awarded is more than half the distance to the goal line, the referee will just give half the distance to the goal. Penal fouls occurring in the end zone are usually placed on the 1-yard line or just barely outside the end zone, depending on the league's rules.
In the NFL, the penalty is 15 yards. In college, the penalty is 10 yards.
15 yards
A ten yard penalty. (1st and 10 to 1st and 20)
The penalty spot is 12 yards from the goal line.
15 yards and an automatic first down.
20
The penalty area is 18 yards deep and 44 yards wide.
All players, except the penalty taker must be at least 10 yards away from the penalty spot when the penalty is taken. As the Penalty Area extends 18 yards from the goal line, and the Penalty Spot is 12 yards from the goal line, the distance from the Penalty Spot to the edge of the Penalty Area can be as little as 6 Yards. The Arc - not half circle - marks the area outside the Penalty Area, that is within 10 yards of the Penalty Spot, and therefore outside which players must be when the penalty is taken
Unnecessary roughness, unsportsmanlike conduct or delay of game may lead to a fifteen yard penalty in the NFL. There are two kinds, one is five yards and there is a fifteen yard one. But the NFL took out the five yard one in 2008.
The penalty mark is 12 yards from the goal line.
The longest penalty in an NFL game is undefined. A defensive pass interference penalty is assessed from the line of scrimmage to the spot of the foul. If the spot of the foul is 30 yards beyond the line of scrimmage, the penalty is 30 yards. If the spot of the foul is 18 yards past the line of scrimmage, the penalty is 18 yards. If the spot of the foul is 9 yards past the line of scrimmage, the penalty is 9 yards. A defensive pass interference penalty is the only penalty that can be longer than 15 yards.
The penalty is 15 yards if the referees think the face mask was grabbed intentionally and 5 yards if they think it was incidental.