I tried these shoes on in a store so I had the benefit of knowing the size prior to ordering online.  That said, the velcro strap allows for custom fit for the back of the shoe.  I wear between a 9 and 9-1/2 and the European size 40 fit fine in front and in back.  The strap originally hit the ankle bone on one foot but adjusting the velcro strap eliminated that and the shoe was very comfortable the rest of the day.  I would recommend any of the Spring Step shoes.  They are all leather, made with quality and the sandals come with an additional heel when the original one wears down.  Spring Step is my new favorite shoe brand.  Very unusual styles.  You will get lots of compliments on these shoes.