These t-shirts are generously sized.
Small 36-38" chest (20" flat measurement armpit to armpit)
Med 38 - 40" chest (21" flat measurement armpit to armpit)
Large 40 - 42" chest (22" flat measurement armpit to armpit)
XLarge 42 - 44" chest (23" flat measurement armpit to armpit)
XXLarge (2XL) 44 - 46" chest (24.5" flat measurement armpit to armpit)
XXXLarge (3XL) (Navy & Black Only) 46" - 48" chest (25" flat measurement armpit to armpit)
XXXXLarge (4XL) (Navy & Black Only) 48" - 50" chest (26" flat measurement armpit to armpit)