The arithmetic mean human penis is approximately 12.9 to 15 centimetres (5.1 to 5.9 in) in length, the circumference is approximately 12.3 centimetres (4.8 in). There is no scientific relation between either penis size or race, and shoe size or stretched penis size.
A large-scale study assessing penis size in thousands of 17- to 19-year-old males found no difference in average penis size between 17-year-olds and 19-year-olds. From this, it can be concluded that penile growth is typically complete not later than age 17, and possibly earlier. Physiological functions UrinationArtery: Penile artery, Dorsal artery of the penis, .
The average size of an erect human penis is between 13 – 16 cm (5.1– 6 in). The average circumference of a penis is 12.3 cm (4.85 in) when fully erect. The penis grows bigger during puberty. At the start of puberty, the average length of the penis is 6 centimetres (2.4 in). The penis reaches adult size about 5 years later.