I am very happy with these slippers.  They are light and comfortable and because of the sole, I am able to step outside too.  I usually take a size 8 1/2 or sometimes size 9 depending on the shoe, so I ordered size 9.  The slipper surprisingly feels a little snug but still comfortable.  I think a size 10 would have beent too big... but not sure.  Keep that in mind when you place your order.