My son is 6 years old and this fits him perfectly-size small. It was meant to be for my 3 year old, we ordered the Boba Fett for my 6 y/o, but this came first and big brother put it on thinking it was for him! :) This is going to be too big for my 3 year old but that is ok, he won't care. The belt is too big, will have to alter, but the helmet is awesome. It makes the costume. We just can't unvelcro it too much, once you have it stuck together you may not get it back that way again. Luckily it fits over his head w/o having to undo it. For the price, it is an awesome costume.