Width is measured across the chest below the sleeves from seam to seam. Height is measured from the bottom of the shirt to the highest point on the shoulder (where the seam meets the neck).

Please note that each product has its own specific sizing chart.
SizeWidth (inches)Height (inches)
Girls Small (6/7) - Light Blue1219
Girls Medium (8-10) - Light Blue1320
Girls Large (12-14) - Light Blue14.522.5
Girls XL (16) - Light Blue1625
Girls 4 - Light Blue11.518.5
Girls 5-6 - Light Blue1219
Girls 6X - Light Blue12.520