It was a birthday present He wears size US10 wide and I thought it was a UK size, I ordered size 9. When the package arrived in Jamaica π―π² it said US9 UK8 EU42. (I was worried it wouldn't fit and it would take too long to get a replacement). So I gave it as a gift and I was really happy that it fit in so well. But if you wear it with thick socks, you'll get 9 1/2 or $10.