Down vs. Synthetic Jackets
Updated:
Nov 24, 2025Table of contents
The age-old insulation debate pits all-natural down against man-made synthetic insulation. The long-time warmth champion, down’s high loft makes it an excellent choice for frigid weather and when comfort is the top priority. But synthetic insulation isn’t going down easily—in fact, it outperforms down in wet conditions and during sweaty activities. Below, we’ll look at how each insulator measures up in terms of warmth, water resistance, durability, and more. Will it be a draw between the two, or will one end up victorious?
Down Fill Explained
Down refers to the insulating material derived from duck and goose feathers. Contrary to what one might assume, most down is not made up of feathers (which feature a stiff quill and thick fibers) but rather the soft, fuzzy undercoat that lies underneath them on the waterfowl’s chest and belly. These clusters are exceptionally lofty and trap warm air between their wispy fibers. Down’s high loft makes it the coziest, most compressible, and lightest form of insulation—natural or manufactured.
Down quality is measured by its loft, also known as fill power. To determine fill power, manufacturers fill a cylinder with one ounce of down and place a light disc on top to apply gentle compression. After a minute, the height of the down is recorded. A higher fill power denotes loftier down (which translates to high levels of warmth and low weight and bulk), while a lower fill power indicates less efficient down. Down jacket fill powers generally range from about 650 (for budget jackets like the REI Co-op 650 Down) to 1,000 for the most premium designs like the Rab Mythic G. Of course, the amount of down (referred to as fill weight) is also an important part of the equation when determining the warmth of a jacket.
For more on this topic, visit our article Knowledge is (Fill) Power: How to Interpret Sleeping Bag Warmth and Weight.
Synthetic Fill Explained
Synthetic fill is a manufactured insulation that mimics down’s warmth-trapping capabilities. Generally made from polyester sheets or down-mimicking polyester clusters, synthetic fill is sold under trade names such as PrimaLoft, FullRange, CoreLoft, PlumaFill, and Thermoball. Most synthetic insulators can’t compete with down’s loft, warmth-to-weight ratio, and compressibility. However, they still have much to offer in a jacket: Unlike down, they breathe decently well and don’t lose their heat-trapping abilities when wet. Synthetic insulated jackets also tend to be more affordable and durable.
The warmth of synthetic fill is measured in grams per square meter (gsm). This measurement specifies the weight of a meter-by-meter sheet of insulation, with higher numbers indicating heavier insulation. In theory, heavier insulation should correlate with warmth, although this isn’t always the case with cheaper synthetic fill. Synthetic insulation runs the gamut from about 40 to 133-gram weights, with most standard synthetic insulated jackets settling in the 60-gram range, such as the Patagonia Nano-Air (60g FullRange) and Patagonia Micro Puff (60g PlumaFill). Some jackets feature thicker insulation at the core and lighter insulation at the arms and sides.
Hybrid Insulation Explained
Most insulated jackets stick to one lane or the other, using either 100% down or 100% synthetic fill. But a few noteworthy down jackets incorporate some synthetic fill to boost breathability, durability, and water resistance. Arc’teryx’s Cerium Hoody, for example, is primarily filled with down but also features synthetic insulation at moisture-prone areas (whether from sweat or precipitation), including the collar, armpits, cuffs, hood, and back. Similarly, the Norrøna Falketind Down750 and Fjallraven Expedition Pack Down Hoodie feature synthetic insulation at the shoulders for wet-weather resistance and durability under a backpack. These jackets are still down jackets for all intents and purposes, but the added synthetic insulation offers a nice extra dose of performance.
Performance Analysis: Down vs. Synthetic
When it comes to warmth, down is the clear winner. It’s naturally loftier than synthetic insulation, which means it can trap more heat at the same weight or even less. Down-mimicking synthetic insulation like Patagonia’s PlumaFill makes a valiant effort to offer similar warmth for the weight, but it still doesn’t add up. For example, the Patagonia Micro Puff Hoody (which uses PlumaFill and checks in at 10.5 oz.) still isn’t nearly as warm as the Feathered Friends Eos (10.8 oz.). While judging differences in warmth is a subjective exercise and entirely based on anecdotal evidence, there’s a strong consensus amongst the outdoor community that down is the warmer insulator.
Down’s exceptional loft doesn’t just contribute to its warmth—it also makes it highly compressible. As we learned above, the most packable down has a high fill power (around 800 or higher). These down jackets can be stuffed into a corner of your bag or hung from your climbing harness when packed into their pocket or an included stuff sack. As a result, they’re our first choice for space-conscious activities like ultralight backpacking, bikepacking, and alpine climbing. On the other hand, jackets with lower-fill-power down are more comparable to down-mimicking synthetic jackets like the Patagonia Micro Puff or Outdoor Research SuperStrand LT. These are still fairly compressible, but not on the same level as premium down.
One of synthetic insulation’s main calling cards is its ability to insulate when wet. The polyester fibers do not absorb moisture, so they retain their loft in wet conditions and continue to trap warm air. On the other hand, down becomes completely overwhelmed by moisture, losing its loft and, thus, its insulating power—picture a wet cat. For this reason, we always reach for synthetic insulated jackets for wet, drippy conditions or when inclement weather is forecast.
To address down’s shortcomings, manufacturers sometimes apply a water-repellent finish. This finish causes water to bead up and roll off the down rather than soak through. The hydrophobic (“water-hating”) down is then encased in water-resistant shell fabric (Outdoor Research goes the extra mile with its Helium Down, adding a waterproof nylon on the shoulders and hood). In our experience, hydrophobic down adds a nice bit of assurance against dripping ice, wet snow, and light precip, but both the down and the shell will be overwhelmed by sustained moisture. Not only that, but the down’s water-resistant finish wears away over time and will need to be reinforced with treatments like Nikwax’s Down Wash and Down Proof. Efforts like hydrophobic down give you a bit more buffer against light moisture, but a synthetic jacket is still the better choice for wet weather.
We reach for synthetic insulation when we’re gearing up for sweat-inducing cold-weather activities like winter running, ski touring, snowshoeing, and cross-country skiing. Given that down is so effective at trapping air, you may overheat and grow clammy in it as your internal temperature rises. On the other hand, synthetic fill does a much better job of dumping heat and managing sweat. What’s more, many synthetic jackets (like the Arc’teryx Proton) feature supple, stretch-woven shells that are moisture-wicking and feel great even when worn over a t-shirt.
Both down and synthetic insulated jackets are comfortable—but for different reasons. It’s hard to beat the sleeping-bag-like loft of down, especially in super cold conditions. We love pulling up our down puffy’s front zipper and nestling into the lofty, warm collar. But, as mentioned above, down can cause you to overheat even in mild temperatures, and the shiny shell fabric of a down jacket has a decidedly technical feel. Synthetic insulated jackets, on the other hand, offer a different level of coziness—especially those that use a soft, stretch-woven shell fabric. Jackets like the Patagonia Nano-Air, Arc’teryx Proton, and The North Face Casaval feel like your favorite sweatshirt and offer Goldilocks insulation, perfect to wear long after coming indoors.
Down jackets are often viewed as fragile, and it’s true. They generally have thin shell fabrics that can collect an assortment of holes and abrasions over time. And when down jackets spring a leak, you’ll lose down feathers (which translates to warmth) until you can cover it up. For this reason, down isn’t our first choice for jacket-abusing activities like rock climbing, and we recommend opting for a robust shell fabric (like the Rab Microlight Alpine’s 30D) for everyday use. On the bright side, down itself is very durable and does not lose its loft—we have many down hand-me-downs that are over 30 years old and still going strong.
Synthetic jackets flip the script. They’re built with thicker or more pliable shell fabrics that can sustain more hard use—and when they do rip, it’s not as monumental an occasion as a down leak. For example, our Patagonia Micro Puff’s thin 10D shell has sustained over a dozen small holes, but it’s easy to simply poke the PlumaFill insulation back into the jacket until you can slap a patch on. We’re far more likely to choose synthetic insulation over down for winter outdoor work, sitting around a campfire, or rock climbing. However, synthetic insulation itself is not particularly durable: Throughout its lifespan, it will pack out and grow less insulative, especially if compressed frequently and for long periods.
In short, synthetic insulated jackets can take a beating, but the insulation will lose its insulating properties over time; on the other hand, down jackets are fragile and should be treated with care, but down will never lose its loft.
The sustainability debate is always tough when it comes to judging between natural and man-made materials. Down has a troubled history of unethical treatment of ducks and geese, including live-plucking and force-feeding. Much progress has been made to ensure that the waterfowl are treated humanely, including efforts like the Responsible Down Standard (often abbreviated to RDS) and Patagoina’s Traceable Down Standard. These days, it’s rare to see a brand use down that hasn’t been certified by one of these standards, but it’s still something to keep an eye out for.
Synthetics don’t cause overt harm to animals, but they do have their own dark side. These man-made fills are petroleum-based, meaning their production could lead to greenhouse gas emissions and potentially unsafe work environments. They’re also known to shed microplastics when washed, which can make their way to the ocean, drinking water, and food. Most synthetic fills are now made from recycled plastic, which is a great effort we applaud—be sure to look out for them. When washing your synthetic clothing, consider using a washing bag like those from Guppyfriend to prevent stray fibers from entering the wastewater system.
The last thing to consider when it comes to sustainability is the longevity of down and synthetic insulation. Because down does not lose its loft, down jackets can last a very long time. On the other hand, synthetic insulation will pack out over time, no matter how well you store or care for it. The most sustainable solution is of course to buy nothing at all, but if you need a jacket and want one that will last you for the rest of your life, we recommend down over synthetic insulation.
In general, synthetic insulated jackets are more affordable than down jackets. For example, one of the most popular down jackets, the Patagonia Down Sweater Hoody, is $329, while its synthetic insulated Nano Puff Hoody is $289. In the same vein, the Arc’teryx Cerium Hoody (down) is $400, while the Atom Hoody (synthetic) is $300. But in both examples, the synthetic insulated jacket isn’t as warm as the down jacket; bumping up to a synthetic jacket of comparable warmth results in similar price points (consider the $329 Patagonia Micro Puff Hoody and the $350 Arc’teryx Atom SV Hoody). However, many of these jackets will be prohibitively bulky and heavy for backcountry use (the Atom SV, for example, is a whopping 1 pound).
Best Uses
We prefer down jackets for:
Dry and cold environments: Down loses its insulating powers when wet, so it's best used in dry or cold environments.
Low-output activities: Down is built to trap air, meaning it does not breathe very well. As a result, we recommend it only for slow-paced activities or when at rest.
The best warmth-to-weight and packed size: For the warmth that it provides, down is lighter weight and more compressible than any other form of insulation. For this reason, it's a great solution for those who prioritize keeping their gear as streamlined as possible.
Unparalleled loft and coziness: Wearing a down jacket can feel like being curled up in a sleeping bag. It's lofty, soft, and cloud-like.
We prefer synthetic jackets for:
Wet weather: Unlike down, synthetic insulation continues to provide warmth even when wet, making it our top choice for humid environments or when moisture is in the forecast.
High-output activities: Synthetic insulation is more breathable than down, and synthetic insulated jackets also feature soft shell fabrics that wick moisture and allow air to pass through. For this reason, we much prefer synthetic insulated jackets over down for high-output activity in cold weather (like skate skiing, ski touring, and winter running).
Layering: Synthetic insulation isn't as lofty as down, so synthetic insulated jackets are often sleeker and lower-profile. This makes them ideal for layering under a ski, rain, or hardshell jacket.
When durability matters: Synthetic insulated jackets aren't as fragile as down—they're often built with thicker face fabrics. What's more, putting a hole in your synthetic jacket isn't as disastrous as springing a leak with down. For this reason, synthetic insulated jackets are great for outdoor work environments, rock climbing, or heavy use.
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