duh. if the ideal girth is 6.5 inches, that's a dick that's (6.5/3.14159~) = 2 inches wide. i don't know, mine is about like 4.5cm across at the head where it's fattest, and that's something like 1.7 inches, right? and i think i have about an average dick or something like that. so don't get butthurt if your dick is smaller than the graph, because you're probably just the same as everyone else.
as long as you don't have a filthy jewcock.