I wear a size 7 usually, and ordered size 8, based on reviews.  I returned these, as I like to wear socks in them, and were too small.  If you like to wear socks in them, I would order two sizes up from your usual size.  I did not reorder in a size 9, as the toebox is not wide enough and because the bottoms are made of a "plastic material, not rubber, and looked like they would be extremely slippery!