Points to Ponder:
Don't stretch any part of the T-shirt. It must be free from wrinkles. Don't use fabric covered surfaces. Surface must be as flat as board.
Measure around the fullest part of the chest.
The body length is measured from neck seam to the bottom of the T-shirt.
The sleeve length is measured from the shoulder seam to the bottom edge of the sleeve opening.
The sleeve length is measured from the shoulder seam to the end of the wrist.
The sleeve opening is measured along the open edge.
The armhole is measured exactly around the arm at the shoulder joint to the armpit.
The shoulder is measured from the base of the neck to the tip of the shoulder.
The neck opening is measured around the neck below the Adam's apple.
The collar width is measured from the collar seam to the outer edge of the collar.
Placed "X" down from high point of shoulder, "Y" to right of center.
The edges of a T-shirt is finished with a hem, which is turned inside out and stitch line should straight.
Hem is to give not only a neat finish but also to provide weight at the lower edge so that the T-shirt hangs well.