This is my 2nd time ordering Nootkas. The first pair about a year ago was a woman's size 41...they were a bit snug on the instep and the heels, but I managed as they did stretch near the instep a tad. I wanted a bit more room in the heel so I ordered a new pair in mens, sizing it according to the woman's equivalent but it they were snug in the toe and heel, so I exchanged it for a mens 43 and they fit perfect! I love how they keep my feet warm without making my feet sweat. Nootkas Customer Service is wonderful to deal with too!