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 Medium - Kelly Green19.528.5
Adult Large - Kelly Green2129.5
Adult XL - Kelly Green2430
Adult 2XL - Kelly Green2431.5