I normally wear a US 6 to 6.5 (trending on the smaller side of that range) so I ordered a EU 36/5-5.5.  However, it was huge and the tan colored elastic strap was extremely loose.  I could have sized down further to a EU 35, but I think that the elastic would still have been too loose.  The black color option looks like a shimmery microfiber, which was not what I expected. The footbed feels extremely comfortable, but this is still going to go back.