What is the average penis size?

Many scientific research papers have tried to answer the question to which many men want an answer - what is the average penis size?

The published findings are often introduced with background information on men's widespread anxiety about whether or not their penis is big enough, and if sexual partners are going to be satisfied. So what is the truth?

The truth about male genital length and girth might have become obscured by the free and widespread availability of internet pornography.

Perhaps it is no surprise that researchers say men have heightened anxieties about their manhoods. And another aggressive industry pushes dubious promises of a bigger penis through enlargers and extenders.

Unfounded worries about inadequacy are not helped by the fact that a man's own view of his penis automatically makes it look smaller to him than to someone else. This is simply because looking down at the penis from above makes it appear smaller, compared with how it looks straight on, or from the side.

Seeing one's own penis from this unreliable point of view, and comparing it with other men's appendages from a different view, may reinforce false ideas of penis size.

Women seem to care less about penis size than men

Male concern about whether penile size lives up to the desires of females seems to be largely misplaced.

One study, published in the British Journal of Urology International, suggested that while the majority of women, some 85%, were satisfied with the size and proportion of their partner's penis, men were less sure of themselves.¹

Almost half of men in the study (45%) believed they had a small willy - yet the researchers reported that small penis size was actually rare.

Some 170 women answered questionnaires in another study, which found that while they attached some importance to penis size, it was only of "substantial" importance to a "clear minority" of the women.²

While most of men's worries about penis size centre on the length, women are more interested in width, according to one study.³

The study of 50 sexually active undergraduate women reported that penis width was more important to sexual satisfaction than penis length.

When is penis size too small?

Perhaps the best gauge of what is considered to be a small penis is given by the threshold used by doctors for when penile augmentation may be considered.

Researchers publishing in the Journal of Urology studied the penis sizes of 80 "physically normal" men, measuring penile dimensions before and after drug-induced erections. After finding average sizes, they concluded:⁴

"Only men with a flaccid length of less than 4 centimeters [1.6 inches], or an erect length of less than 7.5 centimeters [3 inches] should be considered candidates for penile lengthening."

What is 'normal' or average penis size?

That last study determining the threshold for a small member is one of a number that have measured the penis sizes among groups of men, and worked out an average.⁴

The mean average length for the penises came to:

• 8.8 centimeters (3.5 inches) for the flaccid length
• 12.9 centimeters (5.1 inches) at the erect length.

The study also found that the size of a man's erect penis was not correlated with the size of his flaccid penis - in other words, men with different lengths of floppy penis may have similarly sized willies when hard.

This finding has been supported by a study of 200 Turkish men, in which "flaccid length had little importance in determining erect penile length."⁵

The research to determine average penis size includes a recent study, published in January 2014.⁶

It examined over 1,600 American men, although it did not take independent physical measurements, and instead relied on the men's own measurements of penis size. The reports were probably fairly reliable, however, since the men would then be given condom sizes to match what they said, so that any inaccuracy would have resulted in prophylactics that were baggy or tight.

The study found an average penis size as follows:

• Erect penile length of 14.2 centimeters (5.6 inches)
• Erect penile circumference of 12.2 centimeters (4.8 inches).

The researchers said the self-reported erect penile dimensions were consistent with findings from other studies. Their study added the finding that the precise dimensions of an erection can be influenced by the "mode" of getting aroused - such as whether a man uses "hand stimulation."

More penis measurements

A number of different studies have sought to determine an average penis size. One published in 2001 took measurements of 3,300 young Italian men aged between 17 and 19 years.⁷

It found the median average length of flaccid penises was 9 centimeters (3.5 inches), and the flaccid circumference (at the middle of the shaft) was 10 centimeters (3.9 inches).

Another study examined a different population, of 301 physically normal Indian men, and sought to compare its results with size findings in other countries.⁸

The results, the authors of the 2007 study said, "will help in counseling the patients worried about the penile size and seeking penis enlargement surgery."

• Flaccid: mean average length was 8.2 centimeters (3.2 inches) and circumference (of stretched flaccid penis) was 9.1 centimeters (3.6 inches).
• Erect: mean average length was 13.0 centimeters (5.1 inches) and circumference was 11.5 centimeters (4.5 inches).

The authors concluded:

"There are significant differences in the mean penile length and circumference of Indian sample compared to the data reported from other countries."

The Nature-published paper included a table that listed previous findings on penis dimensions (see previous reports on penile dimensions).

Of the 16 studies they 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 to 10 centimeters (2.8 to 3.9 inches)
• Flaccid circumferences ranged around 9 to 10 centimeters (3.5 to 3.9 inches)
• Erect lengths ranged around 12 to 16 centimeters (4.7 to 6.3 inches)
• Erect circumference (only one previous study) was around 12 centimeters (4.7 inches).

Heightened concerns, 'misguided' desires for enlargement

The authors of the study from India wrote that the definition of normal penile size was of "considerable interest" as there was a "steady increase in the number of people complaining of 'short penis' and seeking penile enlargement procedures."⁸

Other research has suggested that most men who seek surgery to lengthen their penis have an overestimated view of what a normal penis length is.⁹

In the study of 67 men complaining of a short penis, none was, in fact, found to be severely short. The authors said there was an increasing number of men seeking surgery to lengthen their penis.

Written by Markus MacGill

Reviewed by by Silva Neves, a psychosexual, relationship and couple's therapist working in London in the UK.