Studies on penis size
While results vary across studies, the consensus is that the mean human penis is approximately 12.9–15 cm (5.1–5.9 in) in length with a 95% confidence interval of (10.7 cm, 19.1 cm) (or, equivalently, 4.23 in, 7.53 in).[6][7][8] The typical girth or circumference is approximately 12.3 cm (4.85 in) when fully erect. The mean penis size is slightly greater than the median size. Contrary to popular belief, there is no scientific relation between penis size and race.[9][10]
Frequency graph of LifeStyles length data.
Percentile plot of LifeStyles length data.
Frequency plot of LifeStyles circumference data.
Percentile plot of LifeStyles circumference data.
Erect circumference
- The Cancún LifeStyle study, in which the circumference of the shaft was measured at three points (base, mid-shaft, and just below the head) and then averaged, found an average of 12.63 cm (4.972 inches) with a standard deviation of 1.3 cm (0.5 in).[8]
Flaccid length
One study found the mean flaccid penis length to be 3.5 inches (8.9 cm) (measured by staff).[6] A review of several studies have shown average flaccid length to be 9–10 cm.[12] Length of the flaccid penis does not necessarily correspond to length of the erect penis; some smaller flaccid penises can grow much larger, and some larger flaccid penises cannot grow much larger.[