I read reviews saying it runs a bit small, so I bought size 8 (medium) for my 6 year old daughter (48 inches tall, and 45 lbs). It is too big for her. But because it is SOOOO cute, she insists wearing it. I think it will fit her nicely next year. It is well made, and very cute. I don't think it's a practical swimsuit given the feather like white materials below the waist. But my daughter is not entering a swimming competition, and she loves going to swimming pool to wear her swimsuit. So it workSee full review