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 Small1826
Adult Medium1828
Adult Large19.5028
Adult XL22.5028
Adult 2XL2431
Adult 3XL25.5033