MEASUREMENTS The NFL has set measurement rules for the overall length and largest circumference at the center of the football. An official NFL football is slightly larger than high school or other professional leagues. The length should measure about 11 inches from tip to tip, and the in circumference at the center of the football should measure about 22 inches. WEIGHT Overall weight and air pressure are specific in the NFL, too. The football and materials weighs about 14 to 15 oz., and is the ball is inflated to about 12.5 to 13.5 lbs. per square inch. These weight and air pressure measurements create consistency among the many footballs required in a game. MATERIALS The NFL rules also govern the dimension of materials, the number of layers and the pattern of design. Four leather panels are weighed, measured and inspected for blemishes before being sewn together. The top two panels are sewn together with white leather laces. Inside the leather panels is a 3-ply VPU rubber bladder or interior lining that holds the air. INSPECTION Before every NFL football game, the home club supplies 36 footballs for outdoor contests and 24 footballs for indoor ones. An additional 12 footballs are marked with the letter "K," and are used specifically for kicking. The referee inspects every football two hours before the game to ensure it meets the official size, weight and air pressure requirements.