What is the Average Penis Size?

Humans have the largest penis size of any other primate — including the mighty gorilla. 

So how long is the average penis for humans? 

The simple answer to this question is 13.12 cm or 5.16 inches — which is based on research involving well over fifteen thousand men of all different ethnic backgrounds. This same study found the average length of a flaccid penis is 8.9 cm (3.5 inches) long. 

So what does all of this mean? Does it matter if a penis is below or above average length?

Finding the Average Penis Size

Measuring the penis poses a few challenges. For starters, the penis length and circumference can change depending on the ambient temperature, frequency of sexual activity, and level of arousal. Scientists seeking to discover the averages in different men is difficult because you need to account for these factors. 

With that said, there have been several high-quality studies on the subject. We now have plenty of data to determine what the average penis length may be for men at different ages and with different ethnic backgrounds.

There are three ways to measure the size of a penis:

1. Average Flaccid Penis Length

This measures the length of the penis at rest. 

The average flaccid length (measured by researchers) is 8.9 cm (3.5 inches) [3]. 

The length of a flaccid penis doesn’t necessarily correlate to the length of an erect penis. There are a lot of men who have shorter flaccid lengths and longer erect lengths — and vice-versa.

The ambient temperature of the room can dramatically affect the length of the flaccid penis. In cooler temperatures, the cremaster muscle in the penis contracts, pulling both the testicles and the penis closer to the body.

2. Average Stretched Penis Length

This measure involves stretching the penis to its maximum length while flaccid before taking a measurement. 

The average stretched penis length is 13.24 cm (5.21 inches) — which is very similar to the averages found in studies exploring the length of the erect penis. 

3. Average Erect Penis Length 

This measurement looks at the length of the penis while fully erect. The challenge with this measurement is achieving maximum erection before taking the measurement. The measurement process itself can negatively affect arousal and skew the results. 

On average, the erect penis is 13.12 cm long (5.16 inches). The averages can vary from this depending on ethnic background.  

4. Average Penis Circumference

The circumference of the penis can vary a lot. The circumference of a penis is measured mid-shaft — exactly halfway between the base of the penis, and the tip.  

The normal range of penis circumference is between 9 and 16 centimeters (3.5 to 6.3 inches). 

The average circumference was reported to be 11.66 cm (4.59 inches), according to a large systematic review on the subject [1]. 

When is a Penis Considered Short?

From a medical standpoint, a penis with an erect length less than 7.1 cm (2.8 inches) is classified as a micropenis — which is a medical condition where the maximum penis length isn’t achieved during puberty. 

Short Penis & Fertility

From a biological perspective, the length of the penis has little to do with fertility as long as penetration is achieved.

A man with a long penis is no more fertile than a man with a micropenis. 

With that said, some men with a micropenis caused by a lack of testosterone or growth hormone may experience fertility issues from these underlying conditions. It’s not the length of the penis itself that will cause these issues but the hormonal problems that may come along with it. 

Short Penis & Sexual Pleasure

The average vagina is only about 9.6 cm (3.77 inches). In some cases, the vagina can be as deep as 17.7 cm (6.98 inches). On average, the male penis is 33% longer than the vagina is deep. So the vagina can accommodate just about any size of the penis. 

But what if the penis is too short? Do women still experience sexual pleasure from a small penis? 

From a practical standpoint, for women, most of the pleasure experienced during sex doesn’t actually come from penetration directly. The stimulation comes from the clitoris, which is located outside the vaginal cavity. 

Penis length has very little to do with clitoral stimulation, so a man with a short penis can still bring a woman to orgasm. 

Sexual position can also dramatically affect sexual pleasure in men with smaller penises. Check out this collection of sex positions to maximize pleasure if you’ve got less length to work with.

Can a Penis Be Too Long? 

As we’ve already pointed out, the average penis is roughly 33% longer than the average vagina is deep — so the vagina can accommodate a large range of sizes. 

However, some women experience discomfort when their partner has a penis that extends deeper than their vagina can tolerate. During intercourse, the penis hits the cervix, which can cause pain and discomfort. 

There’s no specific length that’s too long. It depends completely on the woman’s depth, as well as the flexibility of the vaginal walls — something that can change with age. 

How to Properly Measure Your Penis

Penis length is measured from the tip to the area that connects to the pubic bone. 

You may need to compress any fat around the base of the penis to get the ruler or measuring tape as closer to the pubic bone as possible. 

Don’t include any extra length from the foreskin. 

The circumference is measured by wrapping a flexible measuring tape around the shaft as close to the middle of the penis as possible. 

Scientific Studies on the Average Penis Size

In 2015, a systematic review measured the penis length and circumference of 15,521 men. This is the best research on the topic to date [1]. The study found that the average penis length was 13.12 cm (5.17 inches), and the average circumference was 11.66 cm (4.59 inches). 

This study is considered the best research on the topic because it was the researchers taking part in the study that did the measurements — rather than the patient himself. 

It seems men can’t help but exaggerate a little when it comes to the size of their penis — even in confidential research studies. 

Studies that record penis size based on self-measurement have reported significantly higher averages than studies where the penis length is measured by researchers. 

For example, one of the largest studies on the subject included the self-reported lengths of 2,770 patients (the largest cohort in a single study to date) [2]. This study reported the average penis length while erect at 15.5 cm — 17% higher than averages obtained by a third-party measurer. 

Scientific Studies on the Ideal Penis Size (According to Women)

Studies have shown that for women, width is more important than length. 

A Dutch study done in 2002 asked 375 sexually active women questions about the ideal size and shape of the penis. 21% of the women felt the length was important, while 77% said the length wasn’t important [4]. 

21% of women in this study favored length over girth, while 32% said girth was more important than length. 

Other studies using 3D modeling of different penis sizes have found that women tend to prefer a smaller penis for long-term mates, compared to one-time sexual encounters [5]. 


  1. Veale, D., Miles, S., Bramley, S., Muir, G., & Hodsoll, J. (2015). Am I normal? A systematic review and construction of nomograms for flaccid and erect penis length and circumference in up to 15 521 men. BJU international, 115(6), 978-986.
  2. Ellis, A. (1948). Kinsey, AC, Pomeroy, WB, and Martin, CE Sexual Behavior of the Human Male. (Book Review). Journal of General Psychology, 39, 299.
  3. Wessells, H., Lue, T. F., & McAninch, J. W. (1996). Penile length in the flaccid and erect states: guidelines for penile augmentation. The Journal of Urology, 156(3), 995-997.
  4. Francken, A. B., Van de Wiel, H. B. M., Van Driel, M. F., & Schultz, W. W. (2002). What importance do women attribute to the size of the penis?. European urology, 42(5), 426-431.
  5. Prause, N., Park, J., Leung, S., & Miller, G. (2015). Women’s preferences for penis size: a new research method using selection among 3D models. PLoS One, 10(9), e0133079.






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