at http://www.hud.gov/offices/reac/pdf/pass_dict2.3.pdf (325 Pages, 343 KB) Additional clarification to these definitions is contained in the REAC PASS Compilation Bulletin which can be found at http://www.hud.gov/offices/reac/pdf/pass_bulletin.pdf (24 Pages, 275 KB)
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.imilar to other levels of football, the NFL uses an egg-shaped football, but the NFL has specific rules to the size, shape and materials used for the football. The Digest of Rules of the NFL explains the official size requirements for the football, along with other basic rules for playing the game.
Canadian football has a larger field (450 ft or 150 yards) long and 195 ft (65 yards) wide. While the NFL has an end zone of 10 ft, the CFL measures 20 yards. The CFL hash marks are set at 51 ft (17 yards).