Bought a size M for my 12 month old daughter, for a recent trip to Turks & Caicos (ridiculously strong sun there!!!!). Hat fit perfectly... it's big on her, but easily adjusted by pulling the toggle. She'll definitely get a lot of use out of it in the next year. She didn't get any burns on her head or face, although she was wearing sunscreen on her face also. Was perfect for the pool when it got wet... stays floppy in the back, and the front is a little more stiff, so it's not falling limply in her face. I've purchased Iplay hats before, the similar style floppy kind, and it's night and day with the fronts. Highly recommend this hat!!!