Do You Actually Need a 1,000-Fill Down Jacket?

Until recently, 1,000-fill down has been a rare commodity. Jackets that included it were always few and far between. But this year, there will be more of it than normal, giving weight weenies new options for ultra-packable warmth. Don’t get too excited, though: quantities will be limited, and prices will be steep relative to what we’re used to. Mountain Hardwear, for example, initially only made 2,000 of its flagship Ghost Whisperer UL ($375), whereas you can likely snag its bestselling 800-fill version, and for $50 less. Is the extra fill power, and two-ounce weight savings, really worth the hunt?

Down Math

Calculating fill power is a helpful way to judge the weight-to-warmth factor of different down jackets. Fill power is a measurement of the quality of the down, and it’s the approximate volume in cubic inches of one ounce of down. So one ounce of 650-fill down takes up approximately 650 cubic inches of space, one ounce of 850-fill down works out to 850 cubic inches, etc. It’s important to note that fill power does not necessarily equate to warmth. Here’s what the numbers mean: Because 1,000-fill down is high in volume, it’s not as dense as other fills and has more room to trap air within the plumage. A jacket with 650-fill down takes up less volume than one with 1,000-fill down, so it’s denser and has less space for warm air. But when it comes to warmth, what really matters is how much of that down is stuffed into the jacket.

We’ll use Mountain Hardwear’s Ghost Whisperer UL as an example. This jacket features two ounces of 1,000-fill down (this important measurement is frequently noted alongside the overall weight of many jackets on the product page, though not every brand lists it), which means the volume of the down is roughly 2,000 cubic inches. Keep in mind that warmth is tied to volume. So a jacket with 2,000 cubic inches of 800-fill down should be just about as warm as an otherwise identical jacket filled with 2,000 cubic inches of 1,000-fill down, like the Ghost Whisperer UL—the 1,000-fill version will just be lighter.

But how much lighter? Using a little high school algebra, we can work backwards, dividing the Ghost UL’s 2,000 cubic inches of down by 1,000 fill to determine that the down weighs two ounces. How does that compare to an 800-fill jacket? The same 2,000 cubic inches (meaning the jacket is exactly as warm) divided by 800 fill yields 2.5 ounces. Even a 650-fill jacket of the same warmth weighs only three ounces. In smaller jackets, the weight difference from 1,000 fill to 850 might be minimal, though the difference could be larger in products like sleeping bags, which use tens of thousands of cubic inches of down.

So while fill power definitely shaves ounces for those looking to slim down their kit, the weight difference in many jackets is minor, and real weight savings are likely to come down to everything around the down. If manufacturers spend big bucks filling their jackets with 1,000-fill down, it’s likely because they’re trying to make them superlight. That means they’ll also try to keep the weight of the fabrics, zippers, and other features to a minimum. But if weight is less of a concern, they might boost durability and function and use cheaper down.

How I Tested

I took these jackets backpacking, ice climbing, and backcountry skiing across the West between the fall of 2019 and the summer of 2020. Temperatures ranged from the low fifties to bitter single digits below zero. Given the variety of jackets and their differing warmths, each generally fell into its own optimal activity and temperature ranges. (The latter is a subjective assessment based on my body, what I was wearing with the jackets, and the activity of the day.)

Mountain Hardwear Ghost Whisperer UL ($375)

Best For: Nerds obsessed with ultralight tech
Weight: 6.7 ounces (men’s medium)
Down Weight: 2 ounces
Optimal Temperature Range: 50 to 35 degrees Fahrenheit

There may never have been a more fully featured down jacket at this weight—or at least I’ve yet to see it. Largely thanks to the featherweight nylon face fabric (or outer layer) that lends its name to the jacket, the Ghost Whisperer line has been able to claim that title for a while. But the brand’s newest iteration swaps out 800-fill down for the primo 1,000 fill and replaces ultralight ten-denier face fabrics with a downright paper-light five-denier version, bringing the Ghost Whisperer UL’s weight to that of a billiard ball.  

That lightweight warmth was enough to take the chill off shoulder-season summits or while making breakfast on summer backpacking trips in Montana’s Beartooth Mountains, when temperatures were in the low fifties. It makes for a toasty midlayer (it fits great under a ski shell) during the colder months, but it’s probably not going to be my only puffy on chilly ski tours (adding a parka would be nice for frigid transitions). And at this level of warmth, the difference between the UL and the 8.8-ounce 800-fill version is really only going to be noticed by picky ounce counters. Cost aside, the weight savings may or may not be worth the paranoia that comes from brushing this jacket against a branch. I babied mine and still saw a few small snags while bushwhacking.

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Eddie Bauer Centennial Collection MicroTherm 1000 ($399)

Best For: Moving while bundled up
Weight: 9.6 ounces (men’s medium)
Down Weight: 3.2 ounces
Optimal Temperature Range: 50 to 30 degrees Fahrenheit

The MicroTherm 1000 only features just over an ounce of additional down compared to the Ghost UL, but Eddie Bauer took few chances on the face fabric with a sturdy (for this category) 20-denier material. Plus, stretchy fleece panels under the arms boost flexibility and breathability.

This jacket kept me slightly warmer than the Ghost Whisperer. I stayed comfortable into temperatures in the high forties without moving. The underarm panels didn’t seem to compromise warmth but were a welcome feature while moving above the tree line during fall hikes up Bear Peak in Boulder, Colorado, with early-morning temperatures in the high forties. The face fabric still deserves some caution around sharp objects, but I felt confident jamming it into my backpack or wearing it while walking over and around blowdown.

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Mont Bell Plasma 1000 ($439)

Best For: Shoulder-season backpacking
Weight: 8.4 ounces (men’s medium)
Down Weight: 3.4 ounces
Optimal Temperature Range: 45 to 25 degrees Fahrenheit

While the  down weight of the Mont Bell is similar to that of the Eddie Bauer, the baffle design of the Plasma 1000 stacks the down a little thicker, making it noticeably puffier and warmer than the Mountain Hardwear or Eddie Bauer jackets. It was my go-to puffy for winter backpacking trips in the desert: I took it down Little Death Hollow to the Escalante River in Utah, where morning temperatures didn’t creep beyond the high thirties. It was also a comfortable jacket for ski transitions on days when the mercury dipped to the low thirties. The seven-denier face fabric feels a little crinkly and lightweight and was just as delicate as the Ghost Whisperer’s—I grazed the cuff over a coarse boulder while hiking along the Escalante and introduced a small tear—but the warmth-to-weight ratio of the Plasma is nearly the best of the jackets I tested. The whole thing packs down to slightly smaller than a 32-ounce Nalgene.

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Rab Zero G ($550)

Best For: Super-cold adventures
Weight: 10 ounces (men’s medium)
Down Weight: 4.05 ounces
Optimal Temperature Range: 35 to 15 degrees Fahrenheit

Bigger puffies like Rab’s Zero G are where the value of 1,000-fill down becomes more apparent. With additional down on the inside (it uses more than twice the down of the Ghost Whisperer), the weight difference between a similarly warm 800-fill jacket could be a lot more obvious. The Zero G was warm enough as an ice-climbing belay jacket or a puffy for full-on winter backpacking up Montana’s Hyalite Canyon. The trade-off, though, is that additional 1,000 fill makes this the most expensive jacket I tested—by more than $110.

The Zero G quickly became my preferred winter puffy on days when the digits dropped well below freezing. Thanks to a ten-denier face fabric, it stayed surprisingly intact (I put one small nick in the body with an errant ice screw in my backpack), even though it saw more use than any of its competitors. 

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