Body Width: Lay garment flat, 1" below the armhole flat measure the garment across the chest.
Body Length: Lay garment flat. Measure from the (highest point of the shoulder)
Sleeve Length: Lay garment flat ( Face down), Measure from the center back neck to outer edge of shoulder seam, then along outer edge to sleeve end.
Sizes can vary from 2-3 centimeters because they are measured by hand. 1inch=2.54cm The size matched on a label can differ from the one you have ordered