What is a good fill weight for a down jacket? – Do You Actually Need a 1,000-Fill Down Jacket?

Until recently, 1000-fill was a rare commodity. The jackets that included it were always few and far between. But this year will be bigger than usual, giving weight weenies new options for ultra-packable heat. However, don’t worry too much: the quantity will be limited and the prices will be high to what we are used to. Mountain Hardwear, for example, originally made only 2,000 of its flagship Ghost Whisperer UL ($375), while it can probably snag its best-selling 800-fill version for $ 50 less. Is the extra energy savings, and two ounces of weight, really worth it?

Down Math

Calculating the filling capacity is a useful way to estimate the weight-to-heat ratio of various down jackets. Filling capacity is a measurement of fluff quality, and it is an approximate volume in cubic inches from an ounce down. So an ounce of 650-fill down takes up about 650 cubic inches of space, an ounce of 850-fill down works at 850 cubic inches, and so on. It is important to note that the filling power is not necessarily equal to the heat. Here’s what the numbers mean: because the 1000-down filler is high in volume, it’s not as dense as the other filled ones and has more room to catch the air in the plumage. A jacket with a filling of 650 takes up less volume than a jacket with a filling of 1000, which makes it more dense and has less space for hot air. But when it comes to warmth, what really matters is how much of that fluff is tucked into the jacket.

As an example, we will use UL Ghost Whisperer from Mountain Hardwear. The jacket features a two-ounce 1,000-fill down (this common measurement is often a page, though each brand lists it), which means it’s about 2,000 inches. Please note that the heat associated with the volume. So a jacket with 2,000 cubic inches of 800 fillers should be as warm as an identical jacket filled with 2,000 cubic inches of 1,000 fillers, like the Ghost Whisperer UL: a version with 1,000 fillers will be lighter.

But how much easier? Using a bit of high school algebra, we can work backwards by dividing 2 ounces of Ghost UL, 000 cubic inches below by 1000 to determine that the fluff weighs two. How does this compare to a jacket made of 800 fillers? The same 2,000 cubic inches (which means the jacket is just as warm), divided into 800 fillers, gives 2.5 ounces. Even a jacket made of 650 fillers of the same heat weighs only three ounces. In small jackets, the difference in weight from 1,000 to 850 may be minimal, although the difference may be greater in products such as sleeping bags that use tens of thousands of cubic inches of down.

So while strength shaves for those looking for weight in many jackets are probably all, if manufacturers spend big dollars filling their jackets with 1,000 padding, it’s probably because they’re trying to make them ultralight. This means that they will also try to minimize the weight of fabrics, zippers, and other features. But if the weight is less of a concern, they could increase durability and functionality and use cheaper down.

How I Tested

I took these packing jackets, ice climbing, and cross-country skiing all over the West between fall 2019 and summer 2020. Temperatures ranged from the low fifties to the fierce single digits below zero. Given the variety of jackets and their different warm-ups, each of them usually fell into their optimal ranges of activity and temperature. (The latter is the subject of an assessment based on my body, what I wore with the jackets, and the activity of the day.)

Mountain Hardwear Ghost Whisperer UL ($375)

mountain-hardwear-1000-fill-jacket_h.jpg
(Photo: Ryan Wichelns)

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 fuller jacket at this weight, or at least I haven’t seen one yet. Thanks in large part to the featherweight nylon face fabric (or outer layer) that gives its name to the jacket, the Ghost Whisperer line was able to claim that title for a while. But the brand’s newest iteration swaps 800-fill for primo1, 000 stuffing and replaces ultralight Ten denier fabrics with frankly paper-light five-denier, bringing the weight of Ghost Whisperer UL to a billiard ball

That weight was enough to take on the peaks in summer travel in Montana. It’s a toasted intermediate layer (it fits perfectly under the ski shell) in the colder months, but it’s probably not the only one I’ve bloated on cold ski hikes (adding a park would be good for cold transitions). And at this heat level, the difference between the UL and the 8.8 oz 800-fill version will really only be noticeable on demanding ounce counters. Beyond the cost, the weight savings may or may not be worth the paranoia that comes from cleaning this jacket against a branch. I babied my own and still saw some slight inconvenience while bushwhacking.

Buy Men’s Buy Women’s


Eddie Bauer Centennial Collection MicroTherm 1000 ($399)

eddie-bauer-1000-fill-jacket_h.jpg 
(Photo: Ryan Wichelns)

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 Micro Therm 1000 has only a little over an ounce down to Ghost UL, but the Bauertook has little on-face capability with the rugged (for this category) 20-den material. In addition, elastic fleece panels under the arms increase flexibility and breathability.

This jacket kept me a little warmer than the ghost whisper. I made myself comfortable at forty feet, not moving. The armpit panels didn’t seem to compromise the heat, but they were a nice feature as he moved over the tree line during fall hikes to Bear Peak in Boulder, Colorado, with early morning temperatures in the forties. The face cloth still deserves some care around sharp objects, but I felt confident to get stuck in my backpack or use it while walking and around blowing down.

Buy Men’s Buy Women’s


Mont Bell Plasma 1000 ($439)

mont-bell-1000-fill-jacket_h.jpg 
(Photo: Ryan Wichelns)

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 downward weight of the Mont Bell is similar to that of the Eddie Bauer, the Plasma 1000 bulkhead design folds down slightly thicker, making it noticeably puffier and warmer than the Mount Hardwear or Eddie Bauerjackets. This was my hyped-up for winter desert hikes: Itook down Little Death Hollow to the Escalante River in Utah, where morning temperature didn’t creep past the high thirties. It was also a comfortable ski-crossing jacket in the days when the mercury was falling at the age of thirty. The fabric of the seven deniers ‘ face feels a bit light and light and was as delicate as that of the Ghost Whisperer: I tested the bracelet on a thick stone as I walked down the Escalante and injected a small tear, but the heat-to-weight ratio of the plasma is almost the best of the stones. It all comes down to a little less than a 32-ounce Nalgene.

Buy Now


Rab Zero G ($550)

rab-1000-fill-jacket_h.jpg 
(Photo: Ryan Wichelns)

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

Large nipples, such as Rab’s Zero G, are where the 1,000-fill down value becomes most obvious. With the extra down inside (which uses more than twice the lower Ghost Whisperer), the weight difference between the equally warm padding and the jacket can be much more obvious. The Zero G was warm enough, like an insurance jacket for ice climbing or bloated for a full winter backpack up to Hyalite Canyon in Montana. The trade-off, however, is that the extra 1,000 padding makes this the most expensive jacket I’ve tried, for more than $ 110.

Zero G quickly became my favorite bloated winter on the days when the numbers fell well below zero. Thanks to the ten-denier face cloth, it remained surprisingly intact (I put a little Nick on the body with a wandering ice screw in my backpack), although it saw more use than any of its competitors.

Buy Now

Leave a Reply