The average length of an adult male’s penis when erect is about twice as long as when it is weak, and if the erect length is greater than 8 centimeters there is usually no problem. There are many factors affecting penile development, including genetic factors and acquired factors, such as prepuce, chromosomal abnormalities, reduced testosterone secretion and nutritional status. At present, the size of the penis lacks authoritative standards, the measurement should pay attention to the way of measurement, with a handheld penis head as straight as possible, so that its length is equivalent to the length of the penis erect, with a ruler to measure the distance from the pubic bone joint before to the tip of the penis head, normal adult male erectile length greater than 8 cm belongs to the normal range, will not affect the normal sex life.