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)
Juvenile 41417.50
Juvenile 5-614.5018
Juvenile 715.5019.50
Toddler 2T11.5013.50
Toddler 3T - Red12.515.5
Toddler 4T1317