Here's proof that you don't need to be an expert tailor to know if a suit fits your body perfectly.  According to Esquire, the only tools you'll need is your hands and a mirror.

thefit.JPG

So the next time you're getting a suit of the rack, keep in mind the following things mentioned below:
  1. Shoulder pads end with your shoulders.
  2. Your flat hand should slip easily into your suit under the lapels when the top (or middle) button is fastened. If you put a fist in, the suit should pull at the button.
  3. The top button of a two-button suit - or the middle button of a three-button suit - should not fall below your navel.
  4. With your arms at your sides, your knuckles should be even with the bottom of your jacket.
  5. Jacket sleeves should fall where the base of your thumb meets your wrist.
  6. Between a quarter and a half inch of shirt cuff should be visible.
  7. One inch of break [in the leg].
If any of these don't fit the way they're supposed to, then you'll need to head to a tailor. Hit the link to learn more.