I usually wear a 7 1/2 in wide shoes, and usually an 8 in medium width shoes. I got these in a 39 and I love them. I wore them all day for the very first time out of the box, which is usually a pretty risky thing to do. But because of the adjustable Velcro straps, they were amazingly comfy. They have good arch support, and they're very easy to walk in. I like them so much I just got a second pair!