Size (inch)	3-4	5-6	7-8	9-11	12-14
Width	13,7	14,5	15,3	17	18,1
Height	16,5	18,1	20,2	22,6	24,6

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.