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 1828.5
Adult Medium 1929.5
Adult Large 21.529
Adult XL 23.530
Adult 2XL 2631.5