For most people it depends on their experience, as they haven't researched the topic that thoroughly and maybe haven't experienced that many first hand. M girlfriend, for instance, has had sex with only two other guys - so twit in HS and her husband, who she met at 18 and married at 19. He was apparently about 5 inches. At 8 inches, I am a monster to her. That may change as she moves on and gets more experience.