The goals-against average projects how many goals a player would allow in a regulation 60-minute game. It is calculated as follows:

Goals-Against Average (GAA) = (Goals Allowed * 60) / Minutes Played

A player's single-game GAA does not always match the number of goals allowed. If a game ends in an overtime tie, the goalie's GAA is slightly less than his goals allowed for the game.

Similarly, if a goalie is pulled for an extra skater prior to the end of regulation, his GAA is slightly higher than his actual goals allowed.

The difference is more pronounced when a goalie is pulled early in a game. For example, using the above formula, a goalie who is pulled after allowing three goals in 10 minutes would have a single-game GAA of 18.00.