I've read numerous vendors that when ordering a jacket to order a size up from what you normally wear. I wear a 36 motorcycle jacket, and it's still big on me, so I'm weary of ordering a 38. Is there a way of measuring the differences? I don't want to find out 38 is way too big when I receive it. I'm a small guy to begin with, so I'm skeptical if I need to order up a size when doing so.

Should I measure my chest for a more accurate number?