Getting a leather jacket to fit your body properly doesn't require a degree in fashion technology. There are some simple rules to follow in order to look more like a runway model and a little less like an extra from 'Mad Max.'
Sleeves: The key component found in the very best leather jackets is high-cut armholes, which keep the jacket close to the body. The sleeves shouldn't be too long – an inch or two above your cuff is perfect. Don't be afraid to try on a jacket one size smaller than you think you might need. Remember that this isn't a bespoke suit: You can't really bring it into your tailor and ask him to take it in a little.
Shoulders: Just like any piece of outwear – from tweed to denim – your leather jacket should embrace your shoulders naturally and not appear to droop. Try raising your arms in a circular fashion: You should have full range of motion but without much of the leather bunching up.
Waist: Repeat after us: "No knee-length leather jackets." In general, the waist of your leather jacket should hover right around your belt line. Of course, some jackets (including the fatigue style) will extend a couple of inches below your belt line. This is okay. A floor-length duster, however, is not.