Polar bears have their blubber. Arctic foxes have their fur. When we want to be outdoors in the cold, we humans have to rely on insulation. Luckily, we’ve figured out how to engineer puffer jackets to keep us toasty in frigid conditions—and the right one will let you ski, snowboard, snowshoe, or hang around camp comfortably even as the mercury plummets. 

Insulation isn’t warm all by itself; the heat actually comes from you. All types of insulation work by trapping body heat in tiny pockets, wrapping you in a cozy cocoon. Many different factors influence how well a given jacket retains heat, including the kind of insulation and the other fabrics used. And it’s important to note that your overall comfort in the cold depends on everything else you’re wearing, too. Think of insulation as part of a layering system, working with your base layers, midlayer, and shell to optimize warmth in different conditions. 

Whether you’re looking for a light jacket to wear ski touring or a heat-trapping machine for winter camping, these considerations will help you choose the perfect insulation.

In this article, you’ll learn:

• The pros and cons of down and synthetic fills
• Design variables, plus materials and feature extras to look for

The Puffy Stuff

The biggest question to consider when it comes to insulation is: down or synthetic? There are a few other options out there, including wool and fleece, but these are the two major players. 

Down 

Made from the lofty plumage of geese and sometimes ducks, down is highly prized as insulation because it’s incredibly lightweight and compressible, yet also incredibly warm. A down jacket doesn’t have to feel bulky to keep you toasty, and it packs down small. Down is also long-lasting and durable. Trade-offs: Down is expensive, dries slowly, and loses its insulating power when wet. Water-resistant treatments have improved down’s performance in bad weather, but synthetics still beat it in extended wet or humid conditions.

You’ll often notice a jacket’s fill power advertised: This is a measure of how lofty, and therefore, warm, it is. They go from about 500 fill on the low end to 900 fill on the premium side: The higher the number, the higher the quality of the down. 

Animal welfare is a concern with down, which is why several certification systems have been developed to ensure that the birds that produced the plumage were treated humanely. The Responsible Down Standard is one such industry-wide system.

If you’re looking for the best warmth-to-weight ratio available, and/or you recreate in primarily cold, dry conditions, down is a great choice.

Synthetic

Designers have been trying to replicate down’s insulating powers with manmade materials for decades, and they’re getting pretty close. Synthetic insulation comes in a variety of forms, from chopped-up fibers to little puffs made to mimic plumage, all designed to loft and trap air the way that down does. Its primary advantage is wet-weather performance: Synthetic fill still insulates when wet, and dries faster. Plus, it’s more affordable. On the down side, synthetics are heavier and bulkier, and they break down a bit faster. 

Synthetic insulation also comes from petroleum. But brands have been improving sustainability by creating recycled and even fully biodegradable fibers, reducing environmental impact.

If you’re often outdoors in humid, wet weather, and/or you’re looking to keep costs down, synthetic insulation is just the ticket.

Blends & hybrids

Insulation isn’t always an either-or choice: Some jackets combine down and synthetic fill to optimize each one’s strengths. One strategy is body mapping, or placing different types of insulation on different parts of the jacket to maximize breathability or reduce bulk where it will give the most benefit. 

Under Construction

Fill type matters a lot, but other construction variables also have an effect on how a jacket performs in the field. 

Quilted vs. baffled

Jackets need some way to keep the insulation evenly distributed—otherwise, it will all migrate into clumps and leave huge cold spots. There are two main ways to keep it in place. One method, called quilted or sewn-in insulation, sews little chambers for the fill straight through the jacket and its liner. This is a cheaper and lighter method, but it does create cold spots along the stitch line. For lighter-weight jackets meant for layering and/or for active use, though, this might not be a problem. 

The other method adds light layers between the jacket’s shell and liner to create baffles, or insulation-filled tubes, without the stitch line. This makes for a warmer jacket—but adds weight and price.

Waterproof vs. water resistant

A jacket’s outer fabric adds some protection from moisture. The question is: How much do you need? A waterproof shell fabric fully shields the fluff, which is great in wet snow or rain. But keep in mind that a waterproof layer will make the jacket less breathable overall, and it’s also less versatile, as you can’t just take off the outer shell when conditions allow. Many other insulated jackets employ a water-resistant shell that’s been treated with DWR. These offer less protection from wet weather, but more breathability, and work well in combination with a separate waterproof shell. 

All the Extras

Consider the following features as you shop.

Hood

A close-fitting hood adds a lot of warmth to an insulated jacket, and some are sized to fit over a helmet. But a hoodless jacket is easier to layer under another shell.

Pockets

Hand pockets provide a place to warm up your fingers as well as stash snacks and maps; chest pockets hold phones or wallets nicely. Interior pockets keep their contents warmer (nice for preserving a phone or GPS’s battery life), and zippers make everything more secure. Check to see if the pockets are placed above a hip belt or harness.

Thumbholes

These add warmth for your hands and help create a breeze-proof seal under your gloves. 

Two-way zipper

Being able to unzip the jacket from the bottom up, too, lets you vent extra heat and access a harness.

All articles are for general informational purposes.  Each individual’s needs, preferences, goals and abilities may vary.  Be sure to obtain all appropriate training, expert supervision and/or medical advice before engaging in strenuous or potentially hazardous activity.