The average length of a nonerect penis is three to four inches. Once erect, the average size of an erect penis is five to seven inches in length and four to six inches in girth, and 85 percent of men fall within this range. Unfortunately, many men compare themselves to other men when they’re in the locker room or elsewhere, when the truth is that most men end up a similar size once erect, supporting the idea that some men are “showers,” meaning they are larger when flaccid, and some men are “growers,” meaning they are smaller when flaccid but increase in size more once erect.
Of course, a man’s erect penis may range in length from less than two inches to 16 or more inches. However, few men are at these extremes; the majority of men fall in the typical range.
The size of a man’s penis is mostly determined by genetic factors and there isn’t much he can do to increase its size.