The average erect penis is 5.16 inches, according to a 2015 scientific review that looked at the flaccid and erect penises of over 15,500 men. In the review, 68% of men measured between 4.5 and 5.8 inches while erect. At 8-inches, you’re in the top 1% of men. (In case you’re interested in girth—i.e., the circumference of your dick— the average penis had a girth of 3.7 inches when flaccid and 4.6 inches when erect.) — Men’s Health