How many centimeters is normal for boys?

The size and thickness of penis vary greatly among individuals, which is closely related to race and genetic factors, and has nothing to do with weight and height. The length of the penis changes with age throughout life. There is no obvious relationship between the size of penis and physical exercise. The penis size of normal China people is generally 8.8 cm, the weak state, elongated state and erect state are 12 cm to 13 cm respectively, and the difference between erect state and weak state is between 30% and 100%. The penis of normal adult males in China is about 6-9 cm in weak state and about 1 1- 18 cm after erection. If it is less than 5 cm when weak and less than 10 cm when erect, it means that the penis is short and the circumference when erect is about 8- 14 cm. The specific value varies from person to person. As long as it doesn't affect normal life, there is no problem.