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)
Infant 12M - Gray Heather1013.5
Infant 18M - Gray Heather11.514.5
Infant 24M - Gray Heather1216.5
Infant 6M - Gray Heather1011.5