My daughter is 5, and she is tall and thin. She is in a size 11 shoe and I bought her tons of 5-7 socks, but they are a little big on her tiny feet. She wears the 3-4 size socks most of the time, and they fit fine to me. I haven't opened a lot of her size 5-7's yet, because she still has some wear out of the 3-4's. hope this helps.