Ok - first, I purchased the small which fits perfectly and I typically wear a 6 1/2 to 7 in regular shoes.  Now, there isn't a lot of extra room, but I prefer that over them being sloppy big.  I love these slippers because I do a lot of standing in the kitchen on hardwood floors and that really can take a toll on my feet so the support and comfort of these slippers makes a world of difference.  Very soft and comfortable...and they stay on my feet without slipping off.  It took a day to "wear in"...seemed to slide a bit left in right at first...but quickly conformed to my foot and fit very well.  Highly recommend.