Ball 1 is often used as decoration or palm handle, and the size is about the size of a palm. No specific value was specified.

No.2 ball is slightly larger than 1 ball and is mostly used by children. In fact, the difference between No.2 ball and 1 ball is not obvious, because there is no specific regulation.

There are strict size restrictions on No.3 soccer ball, and No.3 soccer ball is mostly used as a training ball for children, because for children aged 5- 12, the conventional No.4 and No.5 soccer balls are too big, which is not conducive to children's training. The general diameter is 18CM.

No.4 football is mainly used in five-a-side competition, seven-a-side competition, or football on the field, as well as cage football popular in Europe and America. Some 9-a-side competitions also use this ball, which is generally about 20CM, and is usually between 19.8 cm and 20.4 cm. At the same time, the No.4 football is also used as a training ball for teenagers in junior high school and senior high school as well as small-scale competitions.

Football No.5, a common regular football, is mostly used in adult competitions and training, namely 1 1 man-made, 9-man-made and some field events, and its size is not in centimeters.

Extended data:

The ball for competition should be round, its shell should be made of leather or other recognized materials, and materials that may harm athletes should not be used in its structure.

The circumference of the ball shall not be greater than 7 1 cm or less than 68 cm. At the beginning of the game, the weight of the ball should not exceed 453 grams or less than 396 grams. After inflation, its pressure should be equal to 0.6- 1. 1 atmospheric pressure (sea level), which is equivalent to 600- 1 100g/cm'. During the match, the match ball shall not be changed without the permission of the referee.

Baidu Encyclopedia-Football (Sports)