As many as 45% of men believe they have a small penis. Average length when flaccid was from 7 to 10 centimetres (2.8 to 3.9 inches). Flaccid circumference/girth was between 9 to 10 centimetres (3.5 to 3.9 inches) when flacid. Erect the average length ranged from 12 to 16 centimetres (4.7 to 6.3 inches).3 Aug 2018