Measurements laid flat:
Size S: underarm to underarm 20.5",center back 24.5",sleeve from shoulder seam 10"

Size M:  underarm to underarm 21",center back 25.5",sleeve from shoulder seam 11"

Size L:  underarm to underarm 23",center back 26",sleeve from shoulder seam 10.5"
Size XL:  underarm to underarm 23.5",center back 27",sleeve from shoulder seam 11"

Size 2XL: underarm to underarm 26",center back 27",sleeve from shoulder seam 11"