"My son is a big 3 year old. (46 pounds) And I got the 4/6 size and it fits well. Even a little room for growth our under clothes. The shirt is a good thick quality and the logos are great. The hat is like a soft side infant hat so we took the patch off and put on a brown hat, but the hat it came with fit his big head fine. It was worth the price and he loves it."