They run small.  I only use them on the mat & they work well for that, no slipping.  I normally wear either a 9 or 9.5 but I buy wide widths because of my big fat duck feet.  Based on other reviews, I knew I needed at least a 10 in these shoes - the 10 fits just OK, I can deal with it for an hour or so.  I am surprised that I nearly filled the size 10 to the end of the toe - I would probably buy again but I'd step the size up even further next time.