An official soccer ball has a circumference of 27 to 28 inches and weighs 14 to 16 ounces. This is known as a "size 5" ball, which is used at all levels of competition from ages 12 and older.
The ball must be spherical and composed of leather or another suitable material. The pressure of the ball must range from 8.5 to 15.6 pounds per square inch at sea level. These qualities and measurements must be met by each ball at the beginning of the match, and any balls deemed defective during match play may be replaced by the referee. Standards for soccer ball sizes are set by the Fédération Internationale de Football Association.