I purchased a size 18-24 month and it was sooo small it would not fit a 12 month old. I think you need to order about TWO sizes bigger if you want it to fit.

I bought this product size 3 to 6 months for my 3 months old baby and it is small for him. I can't use it.

This item fits a little tighter. It seems a little short and kept riding up. It is very cute and keeps the baby from sun burning.