I guess I am a bootie slipper kind of gal.  I tried these and they felt like the right size, if I would have gone up, it would have been too large, and for sure couldn't go smaller.  My heel kept slipping up when I walked.  This is very annoying and dangerous on our steep stairs.  Returned them immediately.  Besides they sure aren't pretty to look at either.  Had the Acorn booties previously, and loved them.  Until the black material on the outside started to pill up, and look worn down.  The faux fur was nice and kept it's shape and look.  The memory foam insole is nice, haven't found another insole on a slipper as good as Acorn.  I even bought Tempurpedic at $90 and was GREATLY disappointed with the cushion.  I know, I couldn't believe it either!