The shape of a football is an oval, or in geometrical terms, a prolate spheroid. This shape allows the football to be thrown in air in a flawless spiral fashion as well as bounce in many different directions upon landing. However, the shape of the football was not a product of careful design, but emerged from uncontrollable circumstances.
The first known footballs were created using inflated pig bladders. Pig bladder takes an oval shape when inflated, from which the modern football's particular shape came, according to Time magazine. However, since football evolved from games like soccer and rugby, which use spherical balls, the modern football's shape can also be attributed to a faulty design, as noted by Smithsonian magazine. The spherical ball needed to be inflated several times during the game until the last man responsible for blowing it became tired, which eventually gave the ball its oval shape.
This malfunction of the spherical ball was also reported to have occurred during the first known intercollegiate game in 1869 between Rutgers and Princeton. This initial spherically shaped ball gradually took an oval shape as the different games played in the past began to merge and the rules were standardized. The football officially took its modern prolate spheroid shape in the early 20th century when the forward pass became a part of the game in 1906.
The modern football must comply with certain standards that are set by the National Football League in the NFL Rulebook. The rules state that the football must be made with a leather casing that is pebble grained and of natural tan color. Inside the leather casing must be a urethane bladder that is inflated to 12.5 to 13.5 pounds. The ball must be of a prolate spheroid shape and it must weigh 14 to 15 ounces. The NFL also lists the dimensions of the ball and requires it to be a Wilson hand-selected ball with a signature of the NFL Commissioner.