Sizing refers to the body measurements, not the garment dimensions
HOWTO MEASURE:
NECK: Around the fullest part of the neck, at the base
CHEST: Around the chest, just under the arms and across the shoulder blades
SLEEVE: From the center back of the neck, across the shoulder, and down the arm to the wrist
WAIST: Around the narrowest part of the waist
HIP: Around the widest point of the hips
INSEAM: From the crotch to the anklebone on the inside of the leg