Model is wearing a medium. See size chart below (note measurements are general and may not be exact). Width is armpit to armpit, length is neckline to shirt base.

S- 18"W / 27"L M- 20"W / 28"L L- 21.5"W / 30"L XL- 24"W / 31"L 2X- 25"W / 33"L