I usually wear a 7.5-8 in women's boots (to accommodate heavy socks if necessary), so I bought an 8 and it fits well.  I have quite narrow feet.

This is a very good looking boot.  It's slip-on, and I have average sized calves.  There is a little wiggle room around the calf opening but not too bad, although you'll have to be aware if you drive stick because when I let off the clutch sometimes the back of the boot catches on the underside of the seat.

The tread is great!