12 yards.
The penalty spot.
The penalty spot or penalty mark.
The penalty spot is 12 yards from the goal line.
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
The penalty spot is 6 meters from the center of the goal, centered at the top of the penalty area. There is a second penalty spot that is 10 meters from the center of the goal, and this is used for the sixth and subsequent accumulated foul in the same half of the game.
The penalty for an Illegal Forward pass is a five yard spot foul and loss of down. If an Illegal forward pass is intercepted, the penalty would be declined. There would be no enforcement of the penalty.
It is called the penalty arc. It is to ensure that defenders are 10 yards from the penalty spot when a penalty kick is taken.
The D keeps players 10yds from the penalty spot during a PK. If no D was on the top of the penalty box players would be 6yds from the spot.
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.
According to FIFA "Within each penalty area, a penalty mark is made 11 m (12 yds) from the midpoint between the goalposts and equidistant to them. "
Twelve yards.