To choose the correct size for you, measure your body as follows:
Measure around the middle of your neck (at the Adam's apple), keeping the tape a bit loose.
Measure under your arms around the fullest part of your chest.
Measure around your natural waistline, keeping the tape a bit loose.
Bend your elbow 90 degrees and place your hand on your hip. Hold the tape at the center back of your neck. Measure across your shoulder to your elbow and down to your wrist. The total length is your sleeve length.