Measurement trap
A “100-yard” football field is actually 120 yards long.
100 yd vs 120 yd
The field of play between the goal lines is 100 yards. Add a 10-yard end zone at each end and the full field runs 120 yards.
Standard-defined
Why this is interesting
Everyone knows a football field is 100 yards. That is true of the part the game is played on, not of the rectangle painted on the grass.
How this measurement works
The NFL rulebook defines the full playing field as 360 feet (120 yards) long and 160 feet wide.
The field of play — the stretch between the two goal lines — is 100 yards. Each end of it has an end zone 10 yards deep, and those two end zones make up the other 20 yards.
How certain is this?
Standard-defined — both lengths are specified by the rulebook.
Both lengths come from the same rulebook; they measure different things.
Sources & further reading
National Football League
Official Playing Rules of the National Football League(opens external site)
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