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 Green18.527.5
Adult Medium - Kelly Green2029
Adult Large - Kelly Green21.528
Adult XL - Kelly Green2430
Adult 2XL - Kelly Green2531