The length of the penis after erection reaches twenty centimeters although slightly longer than most cases, but also belongs to the normal range, do not have to worry too much. In our country adult male penis specific length due to genetic and growth and development of the environment and other different situations, there will be some differences, although the normal length of our adult male penis after erection in the range of 7 to 16 centimeters, but due to the different measurement tools measurement method, as long as it is not too much impact on the normal sex life and mental health, can be considered normal. Penis twenty centimeters is already enough to meet the daily sex life or mental health needs, in most cases more than 7 centimeters of penis length can meet most of the needs of sexual life, too long penis will be on the female vagina cervix and other damage.