To measure, use a coat that you already have and that fits you well, close the buttons and lay it flat on a flat surface (large table or floor) and proceed as follows
A: Measure the Shoulder width from sleeve inset seam to sleeve inset seam.
B: Measure half the Chest measurement from lower axillary point to lower axillary point, lying flat. Take the value multiplied by 2 for the entire chest circumference.
C:Measure the sleeve length from the highest point of the sleeve (usually at the shoulder seam) to the sleeve hem.