I bought sizes 4-6 for my boys and there is no way they will fit up to a size 6 boy. They are fitting my sons now who are in a size 3. I bought them to wear on crazy sock days at school so thankfully we weren't planning on a lot of use. They may be able to wear them through size 4 but not bigger than that. My older son is size 6 and could not get them on.