When does your penis stop growing? What you should know

Penis growth typically ends by the late teens, as puberty winds down around the end of adolescence. But it's important to note that not everyone experiences puberty in the same way or on the same timeline. Keep reading to find out when and why penis growth stops and which medical conditions could influence its trajectory.

While most penis growth happens between the ages of 12 and 16, the penis and testicles continue growing after that. Research suggests the penis generally reaches its full size by the late teens.

"Puberty is when testosterone starts to spike," says Seth Cohen, MD, board-certified urologist at NYU Langone Health, specializing in male sexual and reproductive health. That testosterone boost contributes to penis and testicle growth, the development of secondary sexual characteristics (such as body and pubic hair), and sperm production. Boys may have their first ejaculation around this time.

But, Dr. Cohen reminds us, "everybody goes through growth spurts differently. Some people go through a growth spurt when they're 13. Some people continue to have that growth spurt into their high school years, maybe even early college. There is no hard-and-fast rule."

He points out that testosterone might level off at 15, 16, or your early 20s. “Basically, when you stop growing in height, your sex organs also stop growing."

Like everything else during puberty, penis growth happens at different rates and times for different people. The average penis size for teens and adults alike will depend on many factors, with hormones and genetics being front and center.

Find your starter ED treatment

Get started

A number of factors influence penile growth, including hormones, genetics, and overall health.

Hormones, especially testosterone, play an important role in penile growth during puberty. Factors that impact testosterone levels could potentially affect penile growth and development. 

For instance, one study found that boys with obesity had lower testosterone levels and reduced penile growth compared to boys without obesity, suggesting that childhood obesity may also influence penile development.

Genetics may also play a role. Research suggests that numerous genes are involved in normal penile growth, including genes that help regulate male hormones like testosterone and dihydrotestosterone (DHT). Certain genetic mutations that interfere with these processes can affect penile development, potentially leading to stunted penile growth.

What medical conditions can cause penis size loss?

While the penis has typically reached its full size by adulthood, there are some factors that may cause penis size loss including:  

• Peyronie's disease: Peyronie's disease is a medical condition where hard, fibrous tissue forms under the penile skin, causing it to curve or bend. Research suggests Peyronie's disease could contribute to a loss of penile length.

• Diabetes: Some research suggests that diabetes can contribute to penile fibrosis, in which there is a buildup of stiff tissue and a loss of flexible fibers. These changes can contribute to erectile dysfunction (ED), which may make the penis appear smaller during an erection.

• Prostate cancer treatment: Certain prostate cancer treatments can lead to a loss of penis length. Research has linked radical prostatectomy to reduced penile size and androgen deprivation therapy (ADT) to penile shortening. 

Once the penis reaches its full adult size, the average length is 3.61 inches flaccid and 5.16 inches erect. It's reported that 90% of men have an erect penis between 4 and 6 inches. The average adult penis circumference (a.k.a. "girth") is 4.59 inches.

Of course, some guys are at the extremes of penis size on both ends of this scale. Everyone is different, and that’s great.

Surgery, penis pumps, supplements, and exercises such as jelqing all purport to increase penis size. Some of these claims have scientific support; others, not so much. Some of these methods are more likely to result in more pain than gain, up to and including permanent damage to the penis. 

Many of the most dramatic interventions, such as surgery, are typically reserved for people who have a medical problem, such as a micropenis. That's an adult stretched penis size of under about 3 inches. The vast majority of men do not have micropenises, but if you do, your healthcare provider may be able to help.

Less than you might think. In a survey of 52,031 heterosexual men and women, researchers reported that 85% of women said they were satisfied with their partner's penis size, but only 55% of men were satisfied with the size of their penis.

Dr. Cohen frequently sees patients expressing concern about their size and asking about penis enlargements. "At the end of the day, what I really want to do is ask them, 'Is this what your partner asked for, or is this something you think they want?'" he says. "Oftentimes, it's something we falsely believe our partner wants, but in actuality, they don't give a shit. They just want sex." 

Daily Rise Gummies

Help treat BPH symptoms with daily tadalafil gummies

Learn more

There's a lot of natural variation in how and when penis growth happens. Here's how to put that into perspective:

• Skip the comparisons. There's no need to fixate on hitting an exact size milestone. Because timelines vary so much from person to person, comparing yourself to an average isn't a particularly useful measure.

• Be skeptical of quick fixes: Most products and techniques marketed for penis enlargement lack strong evidence, and some carry real risks, so it's worth approaching those claims with some skepticism.

• Watch for changes later in life. If you notice changes in size or shape as an adult — whether related to Peyronie's disease, diabetes, prostate cancer treatment, or another cause — a healthcare provider can help you understand what's going on and what your options are.