Each period is 15 minutes. The intermission between the periods is two minutes. Halftime is 12 minutes, unless otherwise specified.
Found the answer to this question from the "horses mouth" at http://www.nfl.com/rulebook/timing
15 minutes each quarter.
15
Each quarter in the NFL is exactly 15 minutes long.
15 minutes for each quarter. 60 minutes for the whole game.
there is 15 minutes in each quarter plus the time spent with the clock stopped
5 and 15 minutes long
In a football game, a quarter lasts for 15 minutes. After 2 quarters comes the halftime, when the players take a break (usually 15 minutes) before they come back to the game.
There are about 15 minutes in each quarter of a NFL football game. There are 4 quarters in a NFL football game, thus making it a hour. Usually, 2 minutes are in between each quarter and 15 minutes in halftime. That makes it 21 minutes of break. So an average football game will take anywhere from 1 and a half hours to 2 hours, depending how many injuries there are.
15 minutes per quarter.
60 minutes of playing; 15 for each quarter
There are 15 minutes in a quarter!
15 minutes per quarter.