The Fit Guide: Coats
Words are fine and dandy, but there’s really one way to determine whether or not your clothing properly fits: trying it on.
Topcoats and trench coats are designed to be worn on top of things. To get the most accurate results, wear your coat over a well-fitting suit jacket.
Disclaimer: These rules are just "standards"—and no one has a "standard" body. Ultimately, the most important indicator of fit is how clothing looks and feels on you. Finding a fit that's right for you is more important than following the rules to a T.
The shoulders of your coat and your actual shoulder bones don’t need to line up exactly. You want it to align with the layer in between—the shoulders of your suit jacket.
Your coat’s armhole should be a little more generous than your suit jacket’s, but still be close-fitting to maximize movement. Look for an inch of extra fabric below the armhole, but no more.
The back of a coat doesn’t have be as fitted as a suit jacket’s, but it should still have a straight silhouette without any bagginess. The fabric should lay smooth throughout—pulling is a warning sign that it’s too small.
Chest and Midsection
Don’t expect the chest and midsection to be as contoured as a suit jacket—it needs to be loose enough to fit over your jacket easily and comfortably. It should still fall straight without any excessive fabric, but look out for lapels that “bow,” or stick out. That’s a clear sign that things are too tight.
Here’s an easy one. You want the sleeves to be long enough to cover the sleeves of your suit jacket, but not so long that they’re in danger of hitting your knuckles.
Length can vary based on height, but in general you never want the hem to fall completely below the knee or come up higher than mid-thigh. Go too long or too short, and there’s a chance the hem will flare out like a skirt.