Sizes (in bold) are as labelled on the garment. Measurements are taken when the garment is laid flat on a table. You can then compare these measurements to something you own that fits you well.
A. Chest is measured across from armpit to armpit
B. Back length is measured from the centre of the collar, down the back, to the hem.
C. Measured from the centre back of the neck, across to the top of the shoulder, then down to the cuff.