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 1827.5
Adult Medium 1929
Adult Large21.531
Adult XL 2432
Adult 2XL 25.532
Adult 3XL 2833