Molds to your feet. I wear an 8.5 and purchased an 8.  It was a little snug for the first day then relaxed for a perfect fit.  As I do not wear socks after a couple of warm weather weeks, they started getting an odor (because of the bottom liner).  I just ues Fabreze and it went away.  Use Armor All to shine them like new. - Crocslady.com tip.