The mass of a basketball varies between 12 ounces and 22 ounces. There are different sizes of basketballs for men's, women's and youth games, as well as mini-balls for small kids.
Men's official basketballs are for male players of at least 12 years of age. These balls have a mass of between 20 ounces and 22 ounces and are 29.5 inches to 30 inches in circumference, according to Nike. Women's official basketballs are ideal for female players of at least 7 years of age and male players from age 7 through 12. The balls have a mass of 18 ounces and are between 28.5 inches and 29 inches in circumference.
Kids under 7 years of age play with balls from 16 ounces to 18 ounces that are 27 inches to 28 inches in circumference. For small kids, there are miniature basketballs of between 12 and 14 ounces that have a circumference of 22 inches to 22.5 inches.
Since 1983, the Spalding basketball has been the official NBA game ball. It has a mass of 22 ounces and is 29.5 inches in circumference. Officials must check approved NBA game basketballs to ensure that they are inflated to between 7.5 and 8.5 pounds pressure. Nine balls must be made available to each team for the pre-game warm-up.