"I was unsure about the size. My son is 6 and wears a size 7. I bought size 10-12. It is too big, however, I didn't buy it for now. I am saving it for several months until he has outgrown the one he currently has. He has another spider man costume that he is fast outgrowing. The price I paid was too good to pass up: half price plus free shipping. If your child wears a size 7 and you need it for now, I strongly recommend you buy size 7-8. It appears to be of good quality, similar to the one he has now and that he has been wearing for over 2 years."