My husband has a 10.5-11 depending on the shoe. I bought a 10 and two 11s to see what would fit. 10's were too small. One of the 11s was smaller than the other, more like a skinny 10.5, and 11 was a skinny 11. We keep size 2 shoes in a size 11, but I don't expect them to age well. This type of water shoe looks awful after a fender ride unless they have reinforced socks, which they don't. In any case, they were reasonably priced and should be suitable for our upcoming cruise.