Packable coats are like the Transformers of adult clothing. While packable windbreakers or down coats don't turn into smaller, vehicular versions of themselves, they can be rolled-up and entirely stored within one of their own pockets. Once packed, such coats can be sealed via a convenient cinched or zipped closure.
A packable coat is important for the same reason Marie Kondo has been having a moment these last few years: we're inundated with stuff, and faced with a shortage of space in which to store it. When a coat can be packed away into its own pocket, it can be stored in a drawer, hardly taking up more space than a pair of boot socks.
Another fact of modern life is that we're living in a smaller world, with more ways of travel and reasons to travel than ever before. This makes a coat that can be compressed for travel an invaluable resource, as you may find yourself leaving or entering wildly different patterns and climates within a matter of hours, all the while holding onto to the same finite number of bags.
Thanks to the ability of a packable coat to be rolled down into a smaller, compressed form, you won't need to carve out precious closet space to hang them. Instead, you can simply store them in a drawer or a cupboard.
Some people with very regular travel schedules, including those that commute each week or weekend, keep a regular packed bag at hand filled with all of their travel necessities. This measure allows them to save precious time, and be ready to travel at the drop of a hat. Packed coats are a must for these ready-to-go-at-all times travel bags.
There's a common perception that packable down coats aren't as warm as their non-packable cousins. However, there is nothing about giving a coat the ability to pack into its pocket that makes it any less warm.
The real marker of warmth is something called "fill power." What fill power measures is the loft (you can also think of it as "fluffiness") of a down jacket. The higher the fill power, the greater the loft. And the greater the loft, the more likely a down jacket is to capture pockets of warm air and keep the wearer insulated.
If you're looking for a packable coat with serious insulation power to match, be on the lookout for a higher fill number. 800 fill power or more should see you through the very toughest of what winter has to offer.
Just as packable down coats are sometimes (mistakenly) seen as being less warm, there is also a tendency to question the water resistant qualities of a packable down coat. However, there is nothing about the packable process that would prevent packable coats from receiving the same treatment that makes non-packable down coats water resistant.
Water resistant packable down coats have the added utility of easy storage in everything from gym bags to even purses. This allows them to be quickly unpacked, worn and deployed to their water-resistant best when a sudden sleet shower or unexpected snowfall crashes your schedule.