DRAPE
A balanced coat drapes easily on your body. When the coat is buttoned, the bottom corners of the front should slighty touch—if they overlap, the jacket’s too large; if they're too far apart, it’s too snug.

SHOULDERS
The slope of the shoulder should follow your own shoulder line, without making you look like a weight lifter or a West Point Cadet.

LENGTH
Today’s suit coats and sport jackets are a bit shorter, but a rule of thumb still applies for men of any height: Traditionally, the jacket should extend to the tips of your thumbs when your hands are extended at your sides. For a more modern fit, it could extend to the base of the thumb.

SLEEVES
Your jacket sleeves shouldn’t look like the sleeves of a roomy topcoat. Nor should they remind you of a skintight sausage case. When you pinch the fabric between your thumb and forefinger and touch your arm, there should be about 1 1/2 inches of fabric between your fingers. Lenghtwise, about 1/4 inch of the shirt cuff should show.

COLLAR
It should hug the back of your neck, showing 1/4 to 1/2 inch of the shirt collar. Also, the top of the jacket right beneath the collar should lie smoothly on your back.

VENTS
Most suit jackets have center vents, which should lie flat. If they separate, it's a sure sign that the coat’s too small. Side vents follow the same rule, especially for a gent with a big butt. The most elegant style is a coat without any vents at all, but it takes a buff build to pull off that look.

LAPELS
On two- or three-button coats, the lapels should lie flat on your chest and roll to your natural waistline. Generally speaking, stick to narrow lapels: Wider styles make you look wider, too.

PATTERN MATCH
A sharp tailor will catch a mis-match in a flash. You can do the same by making sure stripes and plaids line up at three key points: the back of the collar, the breast pocket and the pocket flaps.

BUTTON-STANCE AND ARM-HOLE
Both are higher on coats today, for a style that looks great on a guy with a trim build. If that’s not exactly you, play it safe by sticking with the more classic approach

LAPEL NOTCH
The angle should fall 3 1/2 to four inches below the shoulder seam.

PROPER FIT
The fit of the coat must be generous enough to let you bend your arms and push your elbows forward without any strain.