My feet are usually somewhere between an 8 1/2 and a 9 so I tried the 39 first. They fit but only just barely and according to Dansko's fit guide they were way too small since my toes hit the front of the shoe. So I returned them and got the 40 instead and I am so glad I did! They fit like a dream, I can wear socks with them very comfortably and my feet don't slide out of them when I'm not wearing socks. I definitely need to stretch the tops of them a little but my feet already feel better after wearing them for only a week.