Official size & weight. Indoor; Outdoor; Everywhere. Select the right ball: Official size - Age: 14 & up; Gender: men; Level of play: professional, college & high school. Official 28.5 inch - Age: all; Gender: women; Level of play: professional, college, high school, jr. high & youth leagues. Official 28.5 inch - Age: 14 & younger; Gender: boys & girls; Level of play: junior high, youth leagues. Junior - Age: 12 & younger; Gender: boys & girls; Level of play: grade school & youth leagues.