Scientists do not really know the average length of a penis, but they believe it is probably around 5.1 to 5.5 inches. This is smaller than most people think.

Many people experience anxiety about whether their penis is big enough and if it will satisfy a sexual partner. This can affect a person’s self-confidence and self-image. Often, however, these fears are unfounded.

A 2020 research article notes that most males believe the average length of an erect penis is around 15.2 centimeters (cm) or 6 inches (in). In fact, the average is much smaller.

While sizes vary widely, the average length is probably 12.9–13.97 cm (5.1–5.5 in), and most likely toward the smaller end of this scale. While results vary slightly, most studies estimate the average to be within this range.

In this article, we look at some facts from various scientific studies to try and provide a realistic answer to this question. For many, this will offer reassurance about what to expect of the average penis size.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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In 1996, experts carried out a study that led to a set of guidelines for when a person may need surgery for penis enlargement.

The study measured the penile dimensions of 80 males before and after drug-induced erections.

The researchers concluded that the average penis size was 8.8 cm (3.5 in) when flaccid and 12.9 cm (5.1 in) when erect.

The study also found that the size of a person’s erect penis did not correlate with their flaccid penis size. In other words, a penis may have different lengths when flaccid but similar lengths when erect. They also found no link between age and penis size.

The researchers concluded: “Only men with a flaccid length of less than 4 cm (1.6 in), or a stretched or erect length of less than 7.5 cm (3 in) should be considered candidates for penile lengthening.”

Micropenis and buried penis

Some people are born with micropenis, when a penis is unusually small, usually due to hormonal or genetic factors. A micropenis fulfills the same functions as an average-sized penis, but people may feel dissatisfied with its appearance. Hormonal treatment or surgery can increase its size if a person wishes.

Sometimes, an average-sized penis may appear small due because there is additional skin around it. People may refer to this as a buried penis, and surgery can resolve it.

Experts note that these guidelines are still in use.

Penises vary widely in shape and size. Learn more here.

Ongoing research continues to produce similar findings about penis size.

A 2014 review looked at measurements taken by healthcare professionals for up to 15,521 males aged 17 and over.

The average measurements were as follows:

  • flaccid penis length: 9.16 cm (3.6 in) when stretched
  • flaccid penis girth: 9.31 cm (3.66 in)
  • erect penis length: 13.12 cm (5.16 in)
  • erect penis girth: 11.66 cm (4.59 in)

In 2014, researchers published findings from a study involving over 1,600 males in the United States.

In this study, the average dimensions for an erect penis were 14.2 cm (5.6 in) in length and 12.2 cm (4.8 in) in circumference.

The participants submitted their own measurements and received condoms in exchange. However, self-reported measurements are often unreliable.

A 2019 study found that many males overestimate the size of their penis when self-reporting, especially if they have experienced sexual activity with another person.

The research surveyed 170 college-aged males attending a human sexuality course. Results showed that those with sexual experience with another person were more likely to overestimate than those with no mutual sexual experience.

The authors speculate that sexually experienced men have a “greater sense of masculinity, sexual competence, and prowess.”

Average penis size by country

In 2007, researchers in India produced a table listing findings on penis dimensions from various countries around the world.

Of the 16 studies cited from various countries, the earliest was carried out over a hundred years ago and published in 1899.

They all arrived at similar average penis lengths:

  • flaccid lengths ranged around 7–10 cm (2.8–3.9 in)
  • flaccid circumferences ranged around 9–10 cm (3.5–3.9 in)
  • erect lengths ranged around 12–16 cm (4.7–6.3 in)
  • erect circumference based on only one study was around 12 cm (4.7 in)

Click here to see the table.

How to measure a penis

To measure penis length, press a ruler into the groin and measure from the base of the penis to the tip.

To measure penis girth, wrap a measuring tape around the widest part of the penis.

Some males worry about whether their penis size will live up to the desires of a partner.

However, some older research suggests that penis length is not important for many female partners.

In one study, 77% of females who completed a questionnaire said penis length was unimportant or totally unimportant, compared with 21% who declared it important or very important. Those who said that length mattered to them also stated that girth, or width, was important.

In another survey, 45 out of 50 sexually active undergraduate females said that penis width was more important to sexual satisfaction than penis length.

Get some tips on what to do if you have a thin penis.

A 2015 study asked 75 females to indicate their penis size preferences using 3D-printed models of 33 different dimensions.

The models ranged from 10–21.6 cm (4–8.5 in) in length and 5–17.8 cm (2.5–7 in) in circumference.

The choices varied according to the nature of the relationship that participants were considering.

  • For long-term sexual partners, they chose a length of 16 cm (6.3 in) and a girth of 12.2 cm (4.8 in).
  • For one-time sex partners, they chose a length of 16.3 cm (6.4 in) and a circumference of 12.7 cm (5 in).

Overall, their desired size turned out to be slightly above the averages found across studies.

Health experts have also raised concerns about how anxiety around penis size affects gay males. The Gay Men’s Health Project, based in the United Kingdom, surveyed 586 males. It found that 38% of respondents said their penis size causes them anxiety.

The project urges males to seek help if they have concerns and to remember that, like people, penises come in many shapes, sizes, and skin tones.

One expert suggests that the porn industry may help promote a distorted image of the ideal penis, resulting in anxiety relating to concerns about penis size.

Hormone treatment, surgery, and other techniques can increase the size of a very small penis. However, these treatments carry risks, and most people do not have a small enough penis to warrant these options.

Doctors do not usually recommend treatment unless a penis has a flaccid length of under 4 cm (1.6 in) or a stretched or erect length of less than 7.5 cm (3 in).

Experts highlight concerns about the number of males seeking surgery to lengthen their penis. Often, these people overestimate the size of an average penis.

In one study of 67 males seeking help for a short penis, none were severely short.

According to a 2019 report, motivation for seeking treatment often focuses on self-image, fears of inadequacy, a desire to impress others, and other psychosocial factors.

A 2017 review notes that many people drop the idea of penis enlargement once they understand the risks and possible treatment complications.

Does penis enlargement work? Find out more here.

In 2015, researchers in Saudi Arabia published a study involving 778 males aged 20–82 years attending a urological clinic.

After medically inducing an erection, the researchers took measurements, finding, on average:

  • penis length was 12.53 cm (4.9 in) from the skin over the pubic bone to the penile tip
  • penis length was 14.34 cm (5.6 in) from the pubic bone to the penile tip
  • penis circumference was 11.50 cm (4.5 in)

The researchers also measured the participants’ body mass index (BMI), which increases with obesity. There was a weak correlation between greater BMI and shorter erect penile length when measuring from the skin over the pubic area, but not when measuring from the bone to the tip.

This suggests that the penis appears shorter when there is more fat under the skin at the visible base of the penis. Weight loss can often resolve this.

The researchers also found a small difference in size between males aged 20 years and those aged 70 years, but the difference was less than 1 cm.

Below are some frequently asked questions about the average penis size.

Is 4.5 inches erect a good size?

Penis size varies from person to person. Research suggests the average length of an erect penis probably ranges from 5.1 – 5.5 inches. If a person is concerned about their penis size, they should consider talking with a healthcare professional.

Many males worry about the size of their penis, and this can affect their self-confidence and self-image.

Guidelines that most doctors follow when helping someone decide if they need treatment state that the average size for a flaccid penis is 8.8 cm (3.5 in), while the average size for an erect penis is 12.9 cm (5.1 in).

In addition, research suggests that small penises are relatively rare. Anyone concerned about their penis size should speak with a doctor or sexual health specialist, who can advise them.

Read this article in Spanish.