Drape is one of the hardest style concepts to explain because it’s the hardest to capture. It refers to how a piece of clothing falls and moves on your body. Fit is the most important thing, of course, but I’m sure you’ve had a shirt or coat that fit *perfectly* but was stiff and didn’t move with you and just didn’t look right. Sometimes guys think their fav shirt is great because of the fit, but it’s also likely the drape as well.
Unfortunately, unlike fit which is basically how a fabric is cut and sewn, a big part of drape comes from the qualities of the fabric, which improves with nicer (read: more expensive) options.
An easier illustration to understand drape may come from women's style. Picture the structure of a woman's old school prom dress or a Victorian era ball gown and how stationary that fabric is on the body. Compare that to a modern maxi dress made with a thinner fabric and cut very loosely but is still incredibly flattering to the body because of the way the fabric falls and moves.
Within men's clothing, drape is most often associated with suits and dress pants, usually because these articles use finer fabrics and are enjoyed by men who are attuned to such things, but the concept is equally applicable to casual style. Take this henley, for example. It is not tight – you can tell that by how much extra fabric there is – but the fabric drapes nicely on my body. Imagine a shirt cut from the exact same pattern but made with a stiffer fabric and think of how much boxier and unflattering it would be.
If you've ever wondered why anyone pays some of the prices more expensive clothing gets sold at, drape is one of the most functional reasons. As I indicated above, many people don't even consciously know the flattering drape is the reason they think something looks or fits better, they just know it does. And, if you often find yourself frustrated with clothing that fits but still doesn't seem flattering or feels schlubby, nine times out of ten it's because of the way the fabric and cut drapes on your body. Drape can be especially important for larger men who prefer looser cuts: To avoid looking like you're wearing a shirt that is too large and boxy, focus on finding looser cuts with fabrics that drape in a flattering way. You may be surprised to find you don't need to size up as much anymore.
Like knowing how much salt to add to different dishes, it's important to understand that there aren't products that universally provide “ideal drape” since every body is different and every person has different style preferences. Some may wish to accentuate or disguise some features, or may desire a more structured, relaxed fit.
→ Put it to use: As you try on clothing in the future consider first if it fits, and if it does, how it falls and moves on your shape.