Unbutton the collar, spread the shirt on its back, pull it tight and measure the
inside ring, from the distance between the center of the button to the center of
the button hole.
Spread the shirt on its back with the sleeve angled as straight as possible. Next,
measure from the middle of the yoke line (the yoke line is the stitching that runs
across across the top back) across and past the shoulder until the end of the cuff.
Spread the shirt on it's front and measure from armpit to armpit (the widest part
on the shirt).
Spread the shirt on its front and measure the width across where your belly button
would usually be (typically the narrowest part of the shirt).
Spread the shirt on its back and measure from the middle base of the collar band
to the very bottom of the tail.
Spread the shirt on its back and measure across the yoke line, not the top of the
shoulders. in this example the yoke line is where the stripes go from horizontal