The enduring question now has a scientific answer: 13.12 centimetres (5.16 inches) in length when erect, and 11.66cm (4.6 inches) around, according to an analysis of more than 15,000 penises around the world.

...assembled data from studies where participants had their member measured by a professional.

http://www.theguardian.com/lifeandst...age-penis-size