Square D

Size (cm)	XS	S	M	L	XL
Width	37.5	40	43	46	49
Height	63	65	67	69	70

Size (inch)	XS	S	M	L	XL
Width	14.7	15.7	16.9	18.1	19.2
Height	24.8	25.5	26.3	27.2	27.5

To get good measurements, lay the shirt (preferably the one you love) on a flat, hard surface, then if there are any creases, smooth them out as much as possible

Width: place the ruler from the bottom of the sleeve and measure the width stopping under the other sleeve.

Height: measure from the highest point of the shoulder (top of the collar) to the bottom of the shirt.