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 18.526.5
Adult Medium 19.529
Adult Large 21.530.5
Adult XL 2431
Adult 2XL 2633.5