At What Age Does Penis Growth Start and End?

Learn what size is normal and more

Penis growth does not have one set age limit. However, the growth of the penis is influenced by the hormones of puberty. A person's penis will start to grow more rapidly between ages 10 and 14 but can keep growing until they are between the ages 16 and 21.

Many young people feel concerned or self-conscious about their penis size during adolescence, but most will reach their full penis size by their late teens.

This article discusses when most penis growth occurs, what penis size is considered "normal," and how penis size is measured. It also debunks several myths about penis size.

Penis Growth During Puberty

Many physical changes in the body take place when a biologically male person starts to go through puberty—for example, they will get taller and more muscular.

A young person may also notice that their penis starts to get erect when they are sexually aroused, when they are asleep, and even at other seemingly random times. The testicles will also get larger and pubic hair will grow.

Most penis growth occurs between the ages of 12 and 16. The penis grows in length first and then grows in width (referred to as girth).

Most people reach their fully developed penis size between the ages of 18 and 21.

If you are a young person going through puberty, you may notice that your penis size changes suddenly and fast. Your body, including your penis, may experience rapid changes for a few weeks, and then stay the same for months before changes start happening again.

What Is a Normal Penis Size?

Just like there isn't one age that's the limit for penis growth there's also no single penis size that's normal for everyone.

The average erect penis measures a little over 5 inches long and 4.5 inches around.

Your penis may keep growing for one or two years after you stop growing in height, or for four to six years after your testicles enlarge. However, know that starting puberty later or earlier is not in any way related to the size your penis will eventually be.

If you're measuring your penis, remember that a flaccid penis is smaller than an erect one.

How to Measure a Penis
 Verywell / JR Bee

Myths About Penis Size

Young people may hear many myths about penis size or share them among friends. These misunderstandings and falsehoods can make people worry about their penis size unnecessarily.

  • Erection ability: The size of your flaccid penis does not reflect the size of your erect penis. In many cases, a relatively small flaccid penis gets considerably bigger when erect.
  • Sexual satisfaction: Studies have shown that penis size does not actually matter to the sexual satisfaction of either partner.
  • Link between penis size and other body parts: The size of a person's penis is not related to the size or development of other body parts, such as their hands or feet. Penis size is also not related to how much facial hair a person has or whether they're bald. There is no external or obvious sign that can be used to predict penis size or function.
  • "Manliness:" People who identify as male may worry that their penis size reflects their "manhood", but penis size is in no way related to their physical abilities, personality, or masculinity.

Summary

A young adult's penis grows most rapidly during puberty, especially between the ages of 12 to 16. Some young people experience "growth spurts," when physical changes in their height, muscles, penis size, and pubic hair come on suddenly and move fast.

If you're worried about the size of your penis and think you've passed the age limit for penis growth, know that while people generally reach their full penis size by the time they're in their late teens, there is no single penis size that's "normal."

The size of your penis does not indicate how it will perform during sex or say anything about who you are as a person. As long as your penis functions for urination and sex without pain or other symptoms, you don't need to worry about its size.

A Word From Verywell

It's not uncommon to feel anxiety about penis size, particularly during adolescence. Concerns about penis size usually stem from myths about sexual performance, physical attributes, and "manliness."

As you understand the facts about penis growth and become more confident in yourself, you will likely think less about the size of your penis.

If the size of your penis size is challenging its ability to function, talk to your healthcare provider. You can also get the opinion of a provider with more specialized knowledge who can diagnose and treat conditions related to the penis (urologist).

Frequently Asked Questions

  • When do males start getting pubic hair?

    Pubic hair typically develops around the same time that the testicles and penis begin to grow; generally, between ages 10 and 14.

    However, different hormones control pubic hair growth than those that control penile and testicular growth. That means pubic hair may develop before or after the sex organs start to change.

  • How much does a penis grow during puberty?

    Penis growth varies from person to person. For example, in a study of 6,200 boys, the researchers found that the average penis size increased 4.17 cm (about 1.6 inches) from age 10 to 16.

    While those numbers can give you a general idea of average penis growth, it doesn't tell you about individual growth.

  • Why do erections happen during puberty?

    An erection is when the penis fills with blood and stiffens, which can happen during the day or at night while a person is sleeping. During puberty, it's not uncommon for people with a penis to even experience erections for no reason.

    Erections can also happen before puberty, but they are more common and more frequent during this developmental stage.

6 Sources
Verywell Health 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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By Jerry Kennard
 Jerry Kennard, PhD, is a psychologist and associate fellow of the British Psychological Society.