The official length of a football game in the NFL is 60 minutes, divided into four quarters of 15 minutes each. There are also stoppages for commercials, halftime, and potential overtime, which can extend the game's overall duration. Each quarter's time is managed by the game clock, and once it runs out, the quarter is complete. The game includes various phases, such as plays, timeouts, and various penalties, which can also affect the overall timing.