The precise shape and construction of footballs is typically specified as part of the Sports rules and regulations.
Most modern footballs are stitched from 32 panels of waterproofed leather or plastic: 12 regular pentagons and 20 regular hexagons. The 32-panel configuration is the spherical polyhedron corresponding to the truncated icosahedron; it is spherical because the faces bulge due to the pressure of the air inside. The first 32-panel ball was marketed by Select in the 1950s in Denmark. This configuration became common throughout Continental Europe in the 1960s, and was publicised worldwide by the Adidas Telstar, the official ball of the 1970 World Cup.
Older balls were usually stitched from 18 oblong non-waterproof leather panels, similar to the design of modern volleyballs and Gaelic footballs, and laced to allow access to the internal air bladder. This configuration is still common.
The official FIFA World Cup football for Germany 2006 matches was the 14-panel Adidas +Teamgeist. It was made in Thailand by Adidas, who have provided the official match balls for the tournament since 1970, and is a "thermally bonded" machine-pressed ball, rather than a traditionally stitched one. For future world cups, FIFA is hoping to alternate between Nike and Adidas for match balls.
Another ball with an innovative pattern is the 26-panel Mitre PRO 100T.
There are also indoor footballs, which are made of one or two pieces of plastic. Often these have designs printed on them to resemble a stitched leather ball.
In North America, the term football refers to a ball used to play American football or Canadian football (both of which developed from Rugby football). It is also referred to as a "pigskin", due to their early use of pig's bladder to cover the ball (see Medieval football).
Nearly a prolate spheroid, the ball is slightly pointed at the ends, unlike the more elliptical rugby ball. The Canadian football is slightly less prolate than the American ball and has a closer resemblance to a rugby ball.
The ball is about 11 inches (28 cm) long and about 22 inches (56 cm) in circumference at the center. The exterior of the ball is made of leather, which is required in professional and collegiate football. Footballs used in recreation may be made of rubber or plastic materials.
Leather panels are usually tanned to a natural brown color, which is usually required in professional leagues and collegiate play. At least one manufacturer uses leather that has been tanned to provide a "tacky" grip in dry or wet conditions.
The leather is usually stamped with a pebble-grain texture to help players grip the ball. Some or all of the panels may be stamped with the manufacturer's name, league or conference logos, signatures, and other markings.
Two of the panels are perforated along adjoining edges, so that they can be laced together. One of these lacing panels receives an additional perforation and reinforcements in its center, to hold the inflation valve.
Each panel is attached to an interior lining. The four panels are then stitched together in an "inside-out" manner. The edges with the lacing holes, however, are not stitched together. The ball is then turned right side out by pushing the panels through the lacing hole.
A polyurethane or rubber lining called a bladder is then inserted through the lacing hole.
Polyvinyl chloride or leather laces are inserted through the perforations, to provide a grip for holding, hiking and passing the football.
According to nfl.com: The home club shall have 36 balls for outdoor games and 24 for indoor games available for testing with a pressure gauge by the referee two hours prior to the starting time of the game to meet with League requirements. Twelve (12) new footballs, sealed in a special box and shipped by the manufacturer, will be opened in the officials’ locker room two hours prior to the starting time of the game. These balls are to be specially marked with the letter "k" and used exclusively for the kicking game.
The football used in Australian football is similar to a rugby ball but generally slightly smaller and more rounded. A regulation football is 720–730 mm (28.3–28.7 in) in circumference, and 545–555 mm (21.5–21.9 in) transverse circumference, and inflated to a pressure of 62–76 kPa (9–11 psi). In the AFL, the balls are red for day matches and yellow for night matches
The Australian rules ball was invented by T.W. Sherrin in 1880, after he was given a misshapen rugby ball to fix. Sherrin designed the ball with indented rather than pointy ends to give the ball a better bounce. Before this time, a round ball was used from the 1850s to 1870s and later rugby balls were used to play the game.
Gaelic football is played with a spherical leather ball, roughly 10 in (25 cm) in diameter and 27 to 29 in (69 to 74 cm) in circumference. A dry ball weighs between 370 and 425 grams (13 to 15 oz). The pattern of panels is identical to the volleyball, consisting of six groups perpendicular to each other, each group being composed of two trapezoidal panels and one rectangular panel; 18 panels in all.
Gaelic footballs are also the standard balls used in International rules football.
Although Gaelic football has been played with a round ball since first organised in 1887, balls made by the Irish sports company O'Neills have been used sometime since the company was founded in 1918 and are recognised as the official ball to be played with, although it is now permitted to use the Gaelic ball manufactured by the Irish sports company Gaelic Gear.
Until 1870, rugby was played with a spherical ball with an inner-tube made of a pigs' bladder. In 1870 Richard Lindon introduced rubber inner-tubes and because of the pliability of rubber the shape gradually changed from a sphere to an egg. In 1892 the RFU endorsed ovalness as the compulsory shape. The gradual flattening of the ball continued over the years.
The introduction of synthetic footballs over the traditional leather balls, in both rugby codes, was originally governed by weather conditions. If the playing surface was heavy, the synthetic ball was used, as it didn't absorb water and become heavy. Eventually, the leather balls were phased out completely.
Rugby league is played with a prolate spheroid shaped football. Traditionally made of brown leather, modern footballs are synthetic and manufactured in a variety of colours and patterns. The football used in rugby league is known as "international size" or "size 5" and is approximately 27 cm long and 60 cm in circumference at its widest point. Smaller-sized balls are used for Mini and Mod versions of the game. A full size ball weighs between 383 and 440 grams. Rugby league footballs are slightly more pointed than rugby union footballs and larger than American footballs.
The ball used in rugby union, usually referred to as a rugby ball, is a prolate spheroid essentially elliptical in profile. Traditionally made of brown leather, modern footballs are manufactured in a variety of colors and patterns. A regulation football is 28–30 cm (11–11.8 inches) long and 58–62 cm (22.8–24.4 inches) in circumference at its widest point. It weighs 410–460 grams (14.5–16.2 ounces) and is inflated to 65.71–68.75 kPa (or 9.5–10 psi).
In 1980, leather-encased balls, which were prone to water-logging, were replaced with balls encased in synthetic waterproof materials. The Gilbert Synergie was the match ball of the 2007 Rugby World Cup.