This is a super cute bathing suit, but the bottom in the back is too large. It is not tight but kind of gapes open around my childs bottom. She is five, but is in a size 6  in most everything. I bought her a two XL.  Its not so bad that she probably couldn't get away with wearing it, but it could be better. It also could be fixed by just adding a stitch to tighten it up.