Lay the shirt flat on a smooth surface
Button the shirt and straighten the sleeves
Locate the center back of the collar
Measure from the center back of the collar to the shoulder seam
Continue measuring from the shoulder seam to the end of the cuff
Record the total length
For a dress shirt, use the outside edge of the shoulder seam if needed by the brand’s sizing method
For a shirt with raglan sleeves, measure from the center back of the collar to the cuff along the shoulder line
Compare the measurement with the brand’s sleeve length chart