The average length of a flaccid penis was inches, the average length of a flaccid stretched penis was inches, and the average length of an erect penis was inches. Looking at things another way, the average circumference of a flaccid penis was inches, and the average circumference of an erect penis was inches. It’s a subject many men have wondered about at some point in time: What is the average penis size? According to a study published in the British Journal of Urology International (BJUI), the average length of a flaccid penis is inches, while the average length of an erect penis is skikdainfo.info average girth is inches for a flaccid penis and inches for an erect penis. When erect, average penis size swells to inches in length and inches in skikdainfo.info size is one of the most common sources of insecurity for men.