I just ordered a few pairs of Acorn shoes. I normally wear a 9, but with most of these I seem to be a 10. In this pair, 9 fit. From my experience with this order (all of which I'm returning), Acorn seems to be very confused about feet. All the shoes also had a strange fit: while the arch support on the inside of the foot (you know, where your arch is) is decent enough, the support on the outside side of the foot is more prominent, and there is a bit of a canyon under your foot, between these two. I do not understand it, I do not like it.