I just ordered a pair of Teva Sandals for my son.  He wears a shoe size 11 (as a matter of fact I just bought him a new pair of sneakers that were size 11 and they fit just fine with socks).  Well, the size 11 Tevas were very small for him.  His toes were longer than the front of the shoe so this leads me to believe that they run small.  Ask the seller to measure the shoe for you, and make sure that the length of the shoe is at least 3/4 of an inch longer than the foot (1/2 inch for behind the foot and 1/4 inch for infront of the toes).  You might want to go 1 inch longer than the foot if the heel strap is not adjustable. Dont make the same mistake i made because it will cost me too much to return them so i have to suck up the 24.00 i spent on them.