A Length

Place the end of a measuring tape beside the collar at the top of the garment (high point shoulder). Pull the tape to the bottom of the item.

B Width

Place the end of the tape at the seam under the sleeve and pull the tape measure across the shirt to the seam under the opposite sleeve.

C Sleeve length

Place one end of the tape at the top of the set-in sleeve, then pull the tape down until you reach the hem of the sleeve.