Size 3 balls are the smallest, generally running about 11 ounces and 22 inches in circumference. These are used for games between players who are 8 years old and younger. Size 4 balls weigh about 12 ounces and are 25 to 26 inches in circumference, for players between the ages of 8 and 12.
Size 5 is considered the international standard size soccer ball, used by everyone from World Cup down to age 12 players. Size 5 balls are 14 to 16 ounces and 27 to 28 inches in circumference.Learn more about Soccer/Football