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 - White18.528
Adult Medium - White2029
Adult Large - White21.530
Adult XL - White2429
Adult 2XL - White2631
Adult 3XL - White