Average Penis Size for Boys and Teens

Know When or When Not to Be Concerned

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Adolescence is a time for growth spurts and other changes spurred by the onset of puberty. It can be a time of great uncertainty, as some teens will inevitably fall behind others in their development.

Among the key sexual maturation changes, the testicles get larger and the scrotum begins to thin and redden. In tandem with these changes is the growth of the penis which can develop at different rates for different people.

As sexual awareness increases, concerns about penis size may deepen, particularly if all other signs of puberty (including height, body hair, and changes in voice) are robust. Knowing what to expect—and what an "average" penis size really means—can help alleviate a lot of the stress.

Normal Penis Development

The good news is that penis size is rarely a sign of a medical problem. With that being said, there are few answers about "normal" penis size that will satisfy an emotionally impatient teen.

Between the ages of 10 and 14, when most of the growth spurts occur, teens will often feel the need to "size up" with their peers, believing themselves to fall short if they are anything less than average. Even in kids as young as 11, the visible changes seen in others can quickly turn from a source of curiosity to one of anxiety.

To help dispel these fears, parents need to understand and share the facts about normal penis development with their children if and when it becomes an issue.

Stages of Development

Generally speaking, genitals develop in somewhat predictable stages. According to experts at Stanford Children's Health, the stages of sexual maturation in people with penises break down roughly as follows:

  • Onset of puberty: 9.5 to 14 years
  • First pubertal change: Enlargement of the testicles
  • Penis growth: Around one year after the testicles have started maturing
  • Appearance of pubic hair: 13.5 years
  • Nocturnal emissions ("wet dreams"): About 14 years
  • Other changes (facial hair, a deeper voice, and acne): About 15 years

What is important to note is that, unlike wet dreams and acne, there is no specific age by which the genitals will start to grow. It can be difficult to know exactly when puberty will start and how it will develop.

For some, it may appear as an almost single event. In others, it may develop in fits and starts right through early high school. While siblings often follow similar growth patterns, there can even be variations among them that defy expectations.

Even if a penis appears small by the age of 14, there is still an opportunity for growth. With that being said, many parents will want to schedule an appointment with the family doctor if their child's penis hasn't started to grow after the appearance of body and facial hair. Generally speaking, by the age of 18 to 19, little additional growth can be expected.

Average Penis Length by Age

The average penis length by age, outlined in Adolescent and Young Adult Health Care: A Practical Guide by Lawrence Neinstein, MD, should only serve as a guideline for genital development.

It should not be used to check if a teen is developing "on schedule" (an action that may only underscore insecurity). Rather, it should be used as a reference if your child fears they are falling behind in relation to all other markers for puberty.

The approximate ranges of a non-erect penis by age are as follows:

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

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

Diagnosis of an Abnormal Penis

The diagnosis of an abnormally small penis would seem to be a pretty straightforward process, but it is actually not. While a physical exam may establish that a penis is below what might be expected for a child's age, it cannot accurately predict how much growth may still occur.

However, regardless of age at diagnosis, micropenis is defined as a penis 2.5 deviations smaller than the mean average for the age.

Early diagnosis, in infancy or early childhood, is important for effective treatment. If hormone deficiency is the underlying cause, for example, hormone supplementation can be effective at encouraging catch-up growth.

Other Factors

Keep in mind that there may be factors other than growth that explain a penis' abnormally short appearance. For example, excessive pelvic fat can obscure an otherwise normal-sized penis. The same may occur if a child has a very large frame, creating the impression that the penis is smaller than it is.

Less commonly, there are congenital conditions that limit how much of the penis is externally seen. Examples include penoscrotal webbing (in which the scrotum extends up the underside of the penis, creating an indistinct junction between the two) and phimosis (in which the foreskin is unable to retract).

Small penis size can sometimes occur as a result of a genetic disorder (such as Klinefelter's syndrome) which impedes the production of testosterone during fetal development.

Micropenis Treatment

Generally speaking, after the age of 8 there is little a doctor can do to promote penis growth in boys. For boys 8 and under, testosterone replacement therapy (TRT) may be used; research suggests that it is most effective in infancy and early childhood. Delivered in three intramuscular injections over 12 weeks, TRT may increase the child's penis size to the reference range for their age.

For older boys, surgery may be explored to treat concealed penis abnormalities. The approach can vary by case, but may include circumcision or more extensive reconstructive procedures in which the skin of the penis is "degloved" 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 concerns about penis size may be understandable in teens going through puberty, it is unhelpful for those emotions to be echoed or reinforced by parents or family members. Ultimately, penis size should never be considered a measurement of one's masculinity or virility. These cultural attitudes only serve to undermine teens' confidence at a time when they are only just starting to explore who they are.

If your child is concerned about their penis size, take the time to discuss their feelings without diminishing them. In some cases, penis size may only 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 penis size is emblematic.

Whether the issue is physical or psychological, it often helps to work with a medical professional trained in adolescent health. By allowing an objective third party into the conversation, you can avoid any suggestion that there is a "problem" that needs resolving. Acknowledge your child's feelings and reassure them of their self-worth, but avoid false assurances and platitudes that may only add to their anxiety.

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9 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Stanford Children's Health. The growing child: teenager (13 to 18 years).

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  9. De Jesus LE, Dekermacher S, Anderson KM. Severe forms of concealed penis without hypospadias: Surgical strategies. Indian J Urol. 2015;31(4):344-8. doi:10.4103/0970-1591.163308