I would say 5.5 only because I am 6" and want to be classified as bigger than average lol!!!!!!!!!
lol.
I would say 5.5-6 is average, based on experience and online information etc. Though measurement is a tricky business as half an inch can make the world of difference. I would say measuring from where the shaft appears from the body...i.e not pressing the ruler hard against the body as this, I feel, adds more length than is actually visable/usable.
If you just look at ruler and at the 6.5 inch mark, just looking at it, it seems quite long.
Also I think the bigger insecurites for men come from flaccid size, because a man might be 6 inches flacid and seem realy big, but that might only grow a fraction of an inch when erect, and straight men esentially only see other cocks when they're in a flacid state.
I dont really know much about girth, I would say anything is normal excpet really thin cocks, yuck. haha!