A typical NFL game consists of four 15-minute quarters, each with a 12-minute halftime break. In addition, the clock is stopped for certain situations such as a penalty or a first down. If the game is tight, the referee can also call for an additional two-minute break at the end of the fourth quarter. As a result, the average length of an NFL game is around three hours. Other factors such as a long injury break or a significant number of timeouts can also increase the total length of the game.