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)
Youth Small (6-8) - Navy Heather1722.5
Youth Medium (10-12) - Navy Heather18.523.5
Youth Large (14-16) - Navy Heather1925.5
Youth XL (18-20) - Navy Heather2027