A regulation NHL game is 60 minutes of actual play time; however, the game time lasts approximately two and a half hours with intermissions and timeouts. The length of a game can be extended in the event of a delay or overtime.
There are three 20-minute periods of hockey play with rest intermissions in between them. Each intermission begins directly after period regulation play has expired. Intermissions last for roughly 17 minutes, and play resumes promptly when this time has expired. The official Game Timekeeper provides warnings to the officials and both teams five minutes and two minutes prior to the resumption of regulatory play. The timekeeper also uses an electronic time clock displayed to the audience and spectators to keep them aware of the time left in each period as well as intermissions.