I'm not sure how it fits exactly, because it is a gift for my great-niece's first birthday. However, judging by the dress & how petite she is, I'm going to say it may run a tad small on an average one year old.
As to the dress itself, I could not be happier. It is very nicely made, not a cheap feeling material, and it is just beautiful! My little sweetheart has white-blond hair and very bright intense blue eyes, and  with those adorable pink cheeks, and this dress is going to show her off in style. I can't wait for her party and might have to beg her Mommy to try it on her for a fashion show during the party lol