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 - Light Blue Heather1826.5
Adult Medium - Light Blue Heather19.526.5
Adult Large - Light Blue Heather2127.5
Adult XL - Light Blue Heather23.530
Adult 2XL - Light Blue Heather2530