These are tube socks with no separate heel area so should fit a variety of sizes. They are a bit large on my 4 year old girl (size 8) who I thought they were for: more room in the toe box and they go over the knees. On my 7 year old they are almost perfect. And to be honest, I could probably wear them myself (although they don't go down to my knees)! Size aside, my kids LOVE these socks. My 4 year old daughter slipped them on over her leggings and named each knee.