What is the “official” GaGa Pit size? The official GaGa Ball pit size is 26′ x 26′, which fits up to 28 kids. Other common sizes include: 15′ x 18′ – 12 kids 20′ x 22′ – 20 kids 36′ x 36′ – 44 kids You can adjust the size by 2′ increments by deciding how many walls to put up. Customize your pit to fit your needs!