Men’s Sizing Guide
Adult Small (AS): 29" chest width | 25.3" body length
Adult Medium (AM): 31" chest width | 26.3" body length
Adult Large (AL): 33" chest width | 27.3" body length
Adult XL (AXL): 35" chest width | 28.3" body length
Adult 2XL (A2XL): 38" chest width | 29.3" body length
Adult 3XL (A3XL): 41" chest width | 30.3" body length
 
Youth Sizing Guide
Youth Extra Small (YXS): 21.5" chest width | 17.5" body length
Youth Small (YS): 22.5" chest width | 19" body length
Youth Medium (YM): 23.5" chest width | 20.5" body length
Youth Large (YL): 25.5" chest width | 22" body length
Youth XL (YXL): 27" chest width | 23.5" body length
 
How to Measure:
Chest Width: Measured flat across the front of the garment from armpit to armpit.
Length: Measured from the highest point of the shoulder down to the bottom hem.