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 Small17.5026
Adult Medium18.5027
Adult Large20.5028.50
Adult XL22.5030
Adult 2XL2430
Adult 3XL25.5033