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 18.5027.50
Adult Medium 1929
Adult Large 21.5028
Adult XL 2430
Adult 2XL 2532