Measure across the front from one shoulder seam to the other.
Measure across the front of shirt at the bottom of the side seams.
Measure from the shoulder high point to the bottom hem of the shirt.
Measure across the front from one armpit seam to the other.
SLEEVE LENGTH CB:
Measure from top center of the back down the middle of the sleeve to the cuff.
Measure around the inside of collar from end to end.