Very similar growth curves were found for both penile length and to the literature covering age-specific growth curve and charts about male.
Average penis size. For many at age 16, that’s an average flaccid (not erect) length of about inches and an average erect length between 5 and 7 inches. The girth (circumference) of a flaccid penis and an erect penis average about inches and inchesTrusted Source.
Adolescence is a time for growth spurts and other changes spurred by the onset of puberty. For boys faced with these changes, it can be a time.