I'm a true W6, with slightly wide feet (although I wear regular shoes). I originally ordered a 35N, based on reviews, which was far too small. I then ordered a 36N which had the back of my foot perfectly flush with the back edge, which I still think is a little small. A 37N fits me perfectly, with the room in the front and back that Birkenstock recommends. I also ordered a 35M and 36M when I thought the issue was maybe the wideness of my feet, but trust me-- if you aren't buying special wide shoes in your normal life, the wide is WAY too wide. Just go up a size and you should be fine.The shoes themselves are extremely comfortable. The Soft Footbed requires no breaking in, unlike the normal sole. The suede is very soft on the feet, but they don't stay up, so you can't slip these on to your feet in one move. Overall, I'm very pleased with these shoes, and thankful to Amazon, who let me return four pairs of shoes.