The size of the male friend’s genitalia is doubly concerned, because our sex education knowledge is not popular enough, men often think that the strength of fertility and the size of the genitalia related. And some genitals are not so thick men are not “justified”, penis short is an adult male penis weak, erect after its length, thickness are less than the average normal men’s disease. The human penis and body height. The fat and thin. There are many differences in the size of the features. The length varies. The thickness is not uniform. The average adult male penis is 5-9 cm in length when it is soft. When erect, the length is twice as long as when it is weak. If the length of the penis is less than 4 cm when it is weak. When erect, the length is less than 8 cm. Then it is called short penis.