Question: is 5 inches girth a good size?
Answer: According to the most recent meta study I'm aware of, having 5 inches of girth would put you above 84% of all men (in terms of girth). Which means you're bigger/girthier than 5 out of 6 men. The average is 4.59 inches and the standard deviation is 0.43 inches, if I remember correctly.