The sizing chart is messed up on these slippers, however, I took a chance that they would be sized like any other slipper/houseshoe and they are. I wear 8 1/2 and 9 shoes, so therefore I took a Large. They fit great. When you first get them they will be a bit snug, but after you wear them they stretch a little for perfect fit.  I haven't washed mine yet so that is an unknown.
I love these little slippers. They are so soft and very comfortable, not to hot but keep your feet warm.
I am ordering another pair today in a different color. I got the Ducky first, now we will see. Great price, great slipper.