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The average size of the penis for boys and teenagers

The average size of the penis for boys and teenagers

Adolescence is a period of growth and other changes caused by onset of puberty . For children facing these changes, it can be a time of great uncertainty, as some will inevitably lag behind others in their development.

Among the key changes in sexual maturation , the boys will experience as the testicles enlarge and the scrotum begins to thin and turn red. Along with these changes is penis enlargement, which can develop at different rates for different boys.

As sexual awareness increases, concerns about penis size can deepen, especially if everyone else signs of puberty (including height, body hair and changes in voice ) They are strong. Knowing what to expect and what the «average» size of the penis really means can help alleviate much of the stress.

Normal development of the penis

The good news is that penis size is rarely a sign of a medical problem. That being said, there are few answers about the «normal» size of the penis to satisfy an emotionally impatient teenager.

Between the ages of 10 and 14, when most growth spurts occur, children often feel the need to «test» with their peers, believing that they remain short if they are slightly below average. Even in children up to the age of 11, the visible changes observed in others can quickly go from a source of curiosity to a source of anxiety.

To help calm these fears, parents should understand and share the facts about the normal development of the penis with their children whenever it becomes a problem.

Stages of development

Generally speaking, a child’s genitals will develop in somewhat predictable stages. According to a longitudinal research from the National Institute for Child Health and Human Development, the stages of sexual maturation in children are roughly divided as follows:

  • Beginning of puberty: 9.5 to 14 years
  • First pubertal change: enlarged testicles
  • Penis enlargement: about a year after the onset of the testicles
  • Appearance of pubic hair: 13.5 years
  • Nocturnal emissions («wet dreams»): 14 years
  • Facial hair, voice change and acne: 15 years

What is important to note is that, unlike wet dreams and acne, there is no specific age at which the genitals will begin to grow. In boys, even more so than in girls, it can be difficult to know exactly when puberty and how it will develop.

To some, it may seem like an almost unique event. In others, it can grow in shape and start in high school. While children in a family often follow similar growth patterns, there may even be variations of siblings that defy expectations.

Even if a penis looks small at 14, there is still an opportunity for growth. That being said, many parents will want to make an appointment with their family doctor if their son’s penis has not started to grow after the appearance of facial and body hair.

In general, between 18 and 19 years of age, a small additional increase can be expected.

Average length of the penis depending on age

The average length of the penis depending on age, described in Healthcare for teenagers and young people: a practical guide by Dr. Lawrence Neinstein, should only serve as a guide for genital development in boys.

It should not be used to check whether a child is developing «on time» (an action that can only emphasize the child’s insecurity). Rather, it should be used as a reference if your child is afraid that he is lagging behind all other markers of puberty.

The approximate range of a non-erect penis according to age is as follows: .

  • 10-11 years: 1.6-3.1 inches
  • 12 years: 2.0 to 4.0 inches
  • 13 years : 2.0 to 4.7 inches
  • 14 years: 2.4-5.5 inches
  • 15 years: 3.1 to 5.9 inches
  • 16 years: 3.9 – 5.9 inches
  • Age 17 : 3.9 to 6.3 inches
  • 18 years: 4.3 – 6.7 inches

Because there may be errors in how the penis is measured, it is generally best to have the measurement done by a pediatrician or, better yet, by a teen health specialist.


Diagnosing an abnormally small penis seems like a fairly simple process, but in reality it is not. While a physical exam can determine that a boy’s penis is below what one might expect for his age, he cannot accurately predict how much he can grow. This is especially true for children under the age of 14 who have not yet developed the secondary physical characteristics of puberty.

A physical exam can be most revealing between the ages of 15 and 16 years, when the penis is most likely to grow. But even then, there may be other factors besides growth that explain the abnormally short appearance of a penis.

An example is childhood obesity in which excessive pelvic fat darkens a normal-sized penis. The same can happen if a boy has a very large body, creating the impression that the penis is smaller than it is.

Uncommonly, there are congenital conditions that limit the amount of penis that is seen externally. Examples include penoscrotal membranes (in which the scrotum extends into the lower part of the penis, creating an indistinct junction between the two) and phimosis (in which the foreskin cannot be withdrawn).

Micropenis, defined as a penis with 2.5 deviations smaller than the average age, is an even less likely cause, but can sometimes occur as a result of a genetic disorder (such as Klinefelter’s syndrome) that prevents testosterone production during fetal development.


Generally, after the age of 8, the doctor can do little to promote penis growth in boys. For children under 8 years of age, testosterone replacement therapy (TRT) can be used, but even then, it is actually more effective in children under 3 years of age.

If used early enough, TRT (given in three intramuscular injections over 12 weeks) can increase a boy’s penis size at the age range for his age. After the age of 8, TRT tends to be much less effective.

For older boys, surgery to treat hidden penis abnormalities can be explored. The approach may vary from case to case, but may include circumcision or more extensive reconstructive procedures in which the skin of the penis is «scrapped» and repositioned with sutures and skin grafts.

Penis enlargement surgery (phalloplasty) is not considered a reasonable option until later in life. The risk of complications may outweigh the perceived benefits, and the results tend to be variable at best.

A word from Verywell

While worries about penis size may be understandable in boys going through puberty, it is not helpful for parents or family members to repeat or reinforce those emotions.

Finally, penis size should never be considered a measure of virility or virility. These cultural attitudes only serve to undermine a child’s confidence at a time when they are just beginning to explore who they are.

If your son comes to you worried about the size of his penis, take the time to discuss his feelings without diminishing them. In some cases, penis size may just be a symptom of a larger problem. In some cases, there may have been teasing at school or an underlying lack of confidence for which the size of the penis is emblematic.

Whether it is a physical or psychological problem, it is often helpful to work with a medical professional trained in adolescent health. By allowing a third party to participate in the conversation, you can avoid any suggestion that there is a «problem» that needs to be resolved.

Recognize your child’s feelings and reassure them about their self-worth, but avoid false assurances and platitudes that can only increase their anxiety.