The regulation size for a high school football is a size nine. This is the official size approved for ages 14 and up for play in high school, college and professional football.
American college and professional footballs are required to be made of cow hide leather, according to National Collegiate Athletic Association and the National Football League. While high school football rulebooks allow for the use of a plastic or rubber balls, they are uncommon. Dimensions of a high school regulation-size nine football are between 10.5 and 11.5 inches long from tip to tip, a circumference of 28 inches on the long side of the ball and 21 inches on the short side.