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 1727
Adult Medium 18.5028.50
Adult Large 20.5029
Adult XL 2330.50
Adult 2XL 2431
Adult 3XL 2633.50