Basketball sizes come in variations for different ages, genders, and level of play. The official NBA and competitive professional basketball is 29.5” | 74.9 cm in circumference with a diameter between 9.43”-9.51” | 24-24.2 cm. Professional basketballs must be inflated to a pressure between 7.5-8.5 PSI and cannot exceed the maximum weight of 22 ounces. When choosing a basketball, consider whether the play environment will be primarily outdoor or indoor because indoor basketballs perform best as full-grain leather constructions and outdoor basketballs are better as rubber.