Goals against average (GAA) is a statistic used in ice hockey that is the mean of goals allowed per game by a goaltender or goalie. It is calculated by dividing the number of minutes played by 60 minutes (one game) then dividing the goals against by that answer (the calculation does not count empty net goals or shootout goals). Example: If you allowed 4 goals in 180 minutes your GAA is 1.33 (180 divided 60 = 3. 4 divided by 3 = 1.33). Example: If you allowed 4 goals in 180 minutes your GAA is 1.33 (4 times 60 = 240. 240 divided by 180 = 1.33).