I tried these on in a store in a ten and they were a tad too small so I ordered 1/2 size up from Merrell. I am never more than a ten, but my other barefoot shoes are also a bit snug, so I would recommend ordering a 1/2 size up. I bought these to use indoors not out, for doing my workout videos. They have been totally perfect. They have just enough support for hight impact moves and are super light weight at the same time for ground work and pilates. They are nice and form fitting everywhere (ankle included) but with plenty of toe wiggle room side to side. I have bunions so this is important for me. These shoes are very very comfortable, very light and have zero bulk and nice grip. I assume they would be quite good for road running or brisk walking as well, but mine will stay indoors. Beautiful shoe.