Party Calculator How Much Beer Do I Need? How many adults?(Required)How long is the party?(Required)Number of 12oz Drinks to BuyHiddenLeave Blank CommentsThis field is for validation purposes and should be left unchanged. We use the formula (calculate above): # of adults, divide by 2, multiply by # of hours of the party. Equals how many 12 oz. beers you will need. Give or take a few! 1/2 keg serves 165 (12oz beers) 1/4 keg serves 82 (12oz beers) 1/6 keg serves 55 (12oz beers) What Else Do I Need? Keg deposit Tap Ice (cubes & blocks) Beer cups