I read the reviews prior to ordering so I expected this costume to be big.  It is HUGE.  My daughter wears a 4T so I expected to alter it but we took up 7 inches and then still had to literally cut the fin the day of so that she wouldnt trip.  It was cute but so not worth the hassle.  She had to wear a shirt underneath so that the top wouldn't slide too far down or off her shoulder.  Overall, convince your kid  to dress up as a princess, that's what everyone thought she was anyway.