I carry 10us. I bought $9.5-10 and sent them back because they were too small. I ordered 10.5-11 and they are barely big enough. I can wear them without socks and they are good, but when I put on a pair of socks they are too tight. I think part of the problem is that the top of the heel leans forward and presses the toes against the rather narrow forefoot. Update: 9/12/21 I ended up making a vertical cut under my ankle as my toe was still sore. I soldered the cut. Now they are comfortable.