While results vary across studies, the consensus is that the average
erect 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))
[9][10][11]. The typical girth or
circumference is approximately 12.3 cm (4.85 in) when fully erect.
The average penis size is slightly larger than the median size (or, put another way, most penises are below average in size).
A research project, summarizing dozens of published studies conducted by physicians of different nationalities, shows that worldwide, erect-penis size averages vary between 9.6 cm (3.7 in) and 16 cm (6.2 in). It has been suggested that this difference is caused not only by
genetics, but also by environmental factors such as
culture,
diet, chemical/pollution exposure
[12][13][14], etc. Alarmingly,
endocrine disruption resulting from chemical exposure has been linked to genital deformation in both sexes (among many other problems).
The longest officially documented human penis was a find by Doctor
Robert L. Dickinson. It was 34.3 cm (13.5 inches) long and 15.9 cm (6.25 inches) around. An even larger (but unofficial) measurement was obtained in 1969 by Dr. David Reuben, 35.6 cm (14 inches) long