I got the size 18-24 months to fit our son who was 18 months at the time and has been wearing t-shirts/2 t-shirts for 24 months. It was a bit big but still fit well. The sleeves were a bit longer but I just rolled them up and it was great for the photos. Now that he's 22 months old, that's a good fit. The fabric is not as soft as hoped, but not too scratchy either. The material is thick and lasts a long time.
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