Measure your chest at the fullest part
Measure your waist at the narrowest part
Measure your shoulders from seam to seam or across the back
Measure your sleeve length from shoulder to wrist
Check the jacket brand’s size chart
Compare your measurements to the size chart
Consider whether you want a slim, regular, or relaxed fit
Try the jacket on if possible
Make sure you can move your arms comfortably
Check that the jacket closes without pulling
Choose the larger size if you are between sizes