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 71520
Toddler 2T12.5014.50
Toddler 3T1315.50
Toddler 4T13.5016.50