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) - Lime Green1722.5
Youth Medium (10-12) - Lime Green1723.5
Youth Large (14-16) - Lime Green18.525
Youth XL (18-20) - Lime Green1927