Please order true to your shoe size. They do not stretch.
I have to size down 1 size from what they recommend. They do stretch some in the beginning, enough that I have to add a mid-weight sock, then they are nearly perfect. FYI-Ladies size 6.5 Sandal, size 7(B /Med. Width) Shoe. Wear size 37 in this slipper (with the midweight sock).