I bought a size larger than my shoe size and it worked. I liked the water shoes. They are very comfortable for short distances and do a great job in the water. Here's the problem: no matter how you shake, the sand still won't shake out. It should have a curved edge at the holes in the bottom that will hold the sand. I've collected these things in various ways, even after they dried, but I ended up with a few teaspoons of sand in my suitcase! I threw them away. Too bad.