Provocative Wave for Men

Average Penis Size

What research tells us about average penis size

By Cory Silverberg, About.com

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

Determining the average penis size for a group of males, let alone for men around the world, is more complicated than you might imagine. Unfortunately most information about average penis size comes from popular culture and not science. Let's start by considering some figures from science.

The results from three studies of penis size where the measurements were taken in a laboratory setting give the following ranges:

• Average penis length (flaccid/not erect): from 3.4 inches to 3.7 inches (8.6 cm to 9.3 cm)
• Average penis length (erect): from 5.1 inches to 5.7 inches (12.9 cm to 14.5 cm)
• Average penis girth (circumference when erect): from 3.5 inches to 3.9 inches (8.8 cm to 10 cm)

These numbers are obviously very different from the sizes we hear (and see) in adult movies, and even the kinds of numbers you read on line. Why such a difference?

Many, possibly most, statistics you read are not from legitimate research, but from marketing companies who want you to feel bad about your penis size (so you’ll buy their product).

Important facts about reports of average penis size

• There is much greater variation in size of flaccid (non-erect) penises than of penises when they are erect. A soft penis that looks large may be roughly the same size when erect as a soft penis that looks smaller.
• Because most men see other penises when they are not erect it can appear as if there is a big difference, and men may be likely to assume their erect penis is much smaller when compared to others.
• Male porn stars are often chosen specifically because they have larger than average penises. Also, there are a variety of techniques used to make penises look bigger on camera. Lighting, camera angle, and even shaving of pubic hair can all make things look bigger on camera.

Problems with research on average penis size

Determining what the average penis size is seems like it shouldn’t be that complicated. It’s a physical body part, you measure it, and repeat hundreds of thousands of times around the world, then take an average. Unfortunately, arriving at an accurate idea of what is an average penis size, is more complicated. Some of the problems with figuring out average penis size include:

• Is penis size considered to be the length, the girth, or both?
• When measuring penis length, where do you start?
• Is penis girth measured at the base of the penis, at the glans (head), or around the shaft?
• Are the people measured in these studies representative of the general population?
• Do all studies include measurements taken by others, or self-reported measurements (which are historically bigger than measurements reported by others)?

Different studies answer these questions differently, which makes arriving at a single average penis size almost impossible. Also, many researchers believe that those who are willing to participate in a study about penis size may have larger than average penises, which would also skew the results.