I was really confused what size to get based on the reviews. My daughter normally wears a size 4T shirt, although a couple shirts are still 3T. The size 4T jacket fits her just perfectly with a short sleeve or thin long sleeve underneath. There isn't much give for a sweater though. Also, I wish the hood came down more, as it doesn't cover her forehead at all. The more she moves, the more the hood slides off. Most of the time a good portion of the top of her head is uncovered. I saw some reviews that said their child wears a 4T and they sized up to a girls 5/6. Well I bought that too and it's way too big. I had to roll the sleeves up 3 times. I'm keeping both for when she grows into the bigger one. I just wish the 4T had a little more give and covered her head. She absolutely loves it though.