A regular-season game in the National Hockey League has 60 minutes of playing time broken into three 20-minute periods. There is a 17-minute intermission between each period.
The clock stops on every whistle for a referee to assess a penalty or take other action. These stoppages do not have a set time limit. Accounting for the length of each period, intermissions and stoppages during each game, the average regular-season NHL game lasts approximately two hours and 23 minutes. If the teams participating in the game are tied at the end of regulation, they play a five-minute overtime period immediately following the third period. If the teams remained tied, the teams participate in a penalty shootout of undefined length.