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)
Youth Small (6-8) - Military Green1620.5
Youth Medium (10-12) - Black1722
Youth Medium (10-12) - Military Green1722
Youth Large (14-16) - Military Green1824
Youth XL (18-20) - Military Green18.525.5