How many periods are there in a standard NHL game?

A standard NHL game has three periods. Each regulation period lasts 20 minutes of playing time, for 60 minutes of regulation hockey before any overtime.

The clock stops whenever play is interrupted, so a 60-minute game usually takes much longer in real time. Intermissions separate the three periods, and teams change ends after each period. The three-period structure is distinct from many other sports, where play is divided into halves or quarters.

If the score is tied after regulation, the NHL may add overtime. Regular-season overtime is a five-minute, sudden-death period played three-on-three, followed by a shootout if necessary. Playoff overtime works differently: teams continue with full 20-minute sudden-death periods until someone scores. Those extra periods do not change the answer to the question, because regulation still consists of three periods.