You should take your chest measurements to find out which size is right for you.
How to measure yourself: Measure around the fullest part of your chest with a metric tape measure keeping the tape under your armpits, and then check the table. If you find that you are between two sizes, you should order the smaller size for a tighter fit or the larger size for a looser fit, depending on which you prefer. Remember to take the clothes that you will be wearing under the jacket into account.
