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)
Adult Small - Kelly Green18.526
Adult Medium - Kelly Green20.529
Adult Large - Kelly Green2229.5
Adult XL - Kelly Green23.530.5
Adult 2XL - Kelly Green2530.5