Bought these to use a slippers around the house.  I normally wear a size 8 shoe.  based on other reviews I bought a size 9.  The 9s are a little big.  I would have better off with either an 8 or and 8.5.  If you plan to wear them with socks, go with either your normal shoe size or a 1/2 size up.  Very comfy and warm.  Plus they have good tread on them, you could easily wear them outside if you wanted too.  Great price on Amazon too.  Dick's was selling these for $80 in the store, I paid $40 on Amazon.  Score!