I got cream liners in M/L and black liners in S/M, and both fit. I'm a 8 1/2. They basically cover the bottom of the feet with just enough to come over my toes and on the back of my heal so that they stay on. I wear Terrasoles ballet flats, and together, they're oh so comfy. Unlike other liners that I've tried, these actually stay on the feet and truly don't show. And they keep my feet adequately cool. Love 'em! And the price can't be beat, especially with no tax and no shipping.