The vast majority of beirut (beer pong) games are played with 16oz or 12oz cups. However, there are several colleges where some games are played with 9oz cups. The most notable is Lehigh University in Pennsylvania, where the current incarnation of the game probably originated.

While 16oz tends to be the most popular cup volume for post-collegiate beirut (beer pong) play, 12oz is the preferred cup volume for collegiate play. The discrepancy is probably monetary, and partially due to convenience. 12oz cups are simply easier and cheaper for college students to buy in bulk.