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 18.525
Adult Medium 2028
Adult Large 21.526.5
Adult XL 23.525
Adult 2XL 2326.5