Penis length: the real average

Measured by doctors instead of owners, the average erect cock is about 13 cm long. Here is where that number comes from and why it feels so small

Ask a room full of men how long the average cock is and you will hear six inches, seven, maybe more. Ask a urologist with a ruler and you get a different answer. When the measuring is done by someone else, with the same method every time, the average erect penis is about 13.1 cm5.2 in long. That is the number this site starts from, and it is smaller than most people expect.

It is not a guess. In 2015 a team at King's College London pulled together every study they could find where a health professional had done the measuring, with at least fifty men per study. Men who had surgery, erectile problems or worries about being small were left out. The result was a set of reference charts covering up to 15,521 men, still the most quoted numbers in the field.

The numbers, measured

Length comes in three flavours, and they are not interchangeable. The soft cock hanging normally averages 9.2 cm3.6 in. Pulled gently forward, the stretched length, a stand-in doctors use because it is quicker than getting a patient hard, averages 13.2 cm5.2 in. Fully erect, 13.1 cm5.2 in.

The spread is narrower than porn suggests. Two thirds of men fall between 11.5 cm4.5 in and 14.8 cm5.8 in erect. Only one man in twenty is above 15.9 cm6.3 in, and only one in a hundred passes 17 cm6.7 in. The size chart has the full table, and a calculator if you want to see where you stand.

Why it feels small

Three things make the real average sound like an insult. The first is self-reporting: when men measure themselves, the numbers grow. College men asked for their size answered 16.8 cm on average, and the ones who cared most about looking good gave the biggest figures. When Chinese men were asked to guess and then measured, seven in ten had overestimated.

The second is volunteering. Men who sign up to have their cock measured are, unsurprisingly, often the ones who are happy with it, which pushes study averages up rather than down.

The third is porn. A study of almost 7,000 performer profiles on gay porn sites found sizes that were, in the author's words, extraordinarily large, with tops routinely listed at 8.5 inches and above. Those are advertised numbers, not measured ones, and they set the bar for everyone watching.

Bone-pressed or not

Most of the confusion around length comes from one detail: where the ruler starts. Pushed into the pad of fat above the base until it touches the pubic bone, you get bone-pressed length, the one most studies use. Laid on the skin, you get a shorter figure. In 778 men the difference averaged about 1.8 cm0.7 in, more in heavier men. Losing weight will not grow a cock, but it can uncover one. The details are in How to measure.

Is it getting longer?

A 2023 review of 75 studies from 1942 to 2021 found that erect length went up over time, by about a quarter in 29 years, while soft and stretched length stayed the same. The authors floated earlier puberty as a cause. Others point out that only twenty of those studies measured erections, with different methods, and that a change in who gets measured could explain the rise just as well. Treat it as a question, not a growth spurt.

Small, average, big

There is no official line where big begins. Statistically, anything within one standard deviation of the average is ordinary, which means an erect cock between 11.5 cm4.5 in and 14.8 cm5.8 in is as average as it gets. Above 16.5 cm6.5 in you are in the top two per cent. Medicine only draws a line at the bottom: a micropenis is one more than 2.5 standard deviations below the average, which for adults means under about 9 cm3.5 in erect.

Erect length, measured bone-pressed. Only the micropenis line is a medical definition: the other bands are our own convention, drawn on the percentiles of the measured data, so the jump from average to large is a matter of statistics, not of taste

Gay men, for what it is worth, care about this more than the data deserve. In a survey of over a thousand men who have sex with men, those who rated themselves below average were more likely to call themselves bottoms and less happy overall, while bigger men were more likely to say top. The chapter on size, tops and bottoms looks at what that does and does not mean.