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 - Black 18.529
Adult Large - Black 21.529.5
Adult 2XL - Black 2531
Adult 3XL - Black 26.532.5