I'm so proud when I wear them lol.  I wear size 7, and a woman at a retail store that sells good shoes, measured my feet to be size 37.  They seemed loose at first but I just tightened up the buckle one notch.  The size down would have been too small, birkenstocks are meant to leave room for your toes and heel to expand when you walk.

They took me about a month to break in.  I wore them about 3 times a week and walked from class to class on campus.  The footbed matches my foot like a puzzle piece now.  The footbed also has my sweaty footprint in it now, love it or hate it, my foot has polished the suede(?) Into a shiny smooth texture.

 I also wouldn't recommend these for women with bunions because the thick strap is pretty inflexible.  The strap has actually callused the skin on top of my foot, a bit.  But I could loosen the strap, I just like the tighter feel.  I love birkenstocks, can't wait to collect more of their other styles and  colors.