 The football itself is an oval ball, similar to the balls used in rugby or Australian rules football. At all levels of play, the football is inflated to 12 1 ⁄ 2 to 13 1 ⁄ 2 pounds per square inch (psi) and weighs 14 to 15 ounces (397 to 425 grams); beyond that, the exact dimensions vary slightly. In professional play the ball has a long axis of 11 to 11 1 ⁄ 4 inches, a long circumference of 28 to 28 1 ⁄ 2 inches, and a short circumference of 21 to 21 1 ⁄ 4 inches, while in college and high school play the ball has a long axis of 10 7 ⁄ 8 to 11 7 ⁄ 16 inches, a long circumference of 27 3 ⁄ 4 to 28 1 ⁄ 2 inches, and a short circumference of 20 3 ⁄ 4 to 21 1 ⁄ 4 inches.
