Soccer balls do not come in just one size. Size 5 balls are used for players aged 13 years and up. This is also the size that is use in all Major League Soccer games. Size 4 balls are for players from age 8 to 12 years. Children under 8 years old use size 3 balls. These are the only sizes of balls that are used in competitive play, but there are also two other sizes of balls. There are size 2 and size 1 mini balls that usually have the circumferences of 20