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Western Mountaineering, Feathered Friends, Nunatak, and PhD Lightweight Down Jackets (Comparison Review)


by Alan Dixon | 2001-12-16 03:00:00-07


A lightweight down jacket is a wonderful thing. A down jacket can have up to three to five times more loft than its synthetic counterpart (e.g. a Patagonia Puffball, Moonstone Cirrus, or MEC Northern Lite). The additional loft of down keeps you a lot warmer and makes the jacket ideal for an integrated jacket/bag/bivy system that can save you a bunch of weight. Finally, with the newer water-resistant and breathable outer-shell technologies, the risk of getting the down wet is much lower.

There are more than a few lightweight down jackets on the market. The problem is that the really light down jackets are not stocked in major retail stores. It’s hard to get a close look at just one of them, let alone a number side by side. A few people have taken the plunge and mail-ordered one of these jackets. But given these jackets' high prices, it’s unlikely that anyone has acquired a number of them side by side for comparison. I decided to take the problem on and by various means managed to get four of the better lightweight jackets together for comparison.


  • Nunatak Kobuk
  • Western Mountaineering Down Jacket
  • PHD Minimus Jacket
  • Feathered Friends Helios
  • Comparison Chart and Measuring Loft
  • Microfiber fabrics

Nunatak Kobuk

Nunatak Kobuk 19.3 oz - 4.26 in loft - 0.22 in loft/oz
More Info:

The Kobuk is the jacket I would want if the weather were cold and I had to spend a lot of time in a down jacket. It's a superb lightweight choice for adventurous winter outings or to supplement a lower-rated sleeping bag as part of an integrated bag/jacket/bivy sleep system. Excellent loft, a durable and highly water-resistant Epic shell, cavernous pockets, solid zippers, and generous fit are a few of the plusses of this jacket. This was the heaviest jacket tested but also the most generous in fit, the richest in features, and the best thought out in design. (With the extended rear hem removed, the Kobuk would be in the weight range of the Western Mountaineering and Helios jackets.) The Kobuk jacket feels wonderful when you put it on. Both as measured and subjectively, the medium Kobuk is a bit larger in the torso than the medium Minimus and medium Western Mountaineering down jackets and a lot roomier than the large Helios. The Kobuk was one of the jackets with the highest loft. Chamber fill seemed just right — not too stingy on the down but not so overfilled as to waste down loft by compression.

With the Epic outer shell and 1.3 oz taffeta liner, the Kobuk can probably handle just about anything you can throw at it. Nextec’s Epic is a silicone-encapsulated microfiber fabric that gives the shell enhanced moisture protection and greater durability. (Please see the discussion of shell fabrics at the end of this article LINK.) The Kobuk was the only jacket with a down-filled extended rear hem, which probably added around an ounce of weight. Nunatak will add a down hood to the jacket for an additional $45.

Improvements: Moving a bit of down from the arms to the torso would make the Nunatak a bit warmer without increasing weight. A Velcro flap wrist closure would be nice and is available at no extra charge. I like the Epic fabric, but if light weight were your ultimate goal, you could substitute a Pertex Microlight outer shell (with its DWR). Likewise, if, like me, you aren't sure you see the need for the extended rear hem, you could remove it; and you could use .85 oz nylon for the liner fabric. With these changes, you could get the jacket down to approximately 16 oz. Since Nunatak is a custom shop, you can get just about any variation you want.

Western Mountaineering Down Jacket

Western Mountaineering Down Jacket 17.8 oz - 4.14 in loft - 0.23 in loft/oz
More Info:
Note: Backcountry Gear has the best description of the jacket at:

The Western Mountaineering (WM) down jacket is another solid high-loft jacket with lots of features. The WM jacket uses 1.3 oz nylon for the liner fabric and a new 1.7 oz polyester, Teijin 30/36™ Micro Fiber, for the outer shell. The WM website says the following about this fabric (Please see the discussion of shell fabrics at the end of this article LINK.):

“This proprietary MicroFiber fabric has threads and their filaments so tightly packed that air spaces are few and too small for wind and rain to breach. Since the fabric construction itself is responsible for weatherproofness, it's not something that can wear off, wash out or delaminate. It is built in! This is the most technologically advanced non-laminated weather resistant fabric.”

The WM jacket was the second heaviest of the jackets tested, but it competed with the Kobuk in design and features. Down fill of the chambers seems about right. Front zippered pockets are smaller than the Kobuk’s but are insulated on both sides. The fit is a just a bit snugger than the Kobuk's. Freedom of arm movement is excellent. The jacket has an ingenious interior cargo pocket with a fold-out extension collar that doubles as an excellent stuff sack with drawcord and toggle. This was the only jacket with Velcro flap wrist closures.

Improvements: It's close to perfection. Skip the insulated hand warmer pockets and use light fabric for pocket liners. A bit of the down in the arms could be moved to the torso. With these changes, warmth would be increased and weight should be right around 17 oz.

PHD Minimus Jacket

PHD Minimus Jacket 12.0 oz - 2.97 in loft - 0.25 in loft/oz
More Info:

At 12.0 ounces, the PHD Minimus is the lightest jacket tested. It also is one of the ones with the highest loft per ounce of jacket weight. It has a generous fit and the best arm movement. The Minimus is an excellent choice for summer insulation. It is 2 to 4 ounces lighter than a synthetic fiber jacket (e.g. Puffball Pullover or Moonstone Cirrus) but at 3 inches of loft it has 3 to 3.5 times the loft of the synthetics. The Minimus uses PHD’s proprietary M1 microfiber for both shell and liner. My best guess is that this fabric is similar to WM’s Teijin 30/36 shell but lighter — at a guess, somewhere around .85 to 1.4 oz. (Please see the discussion of shell fabrics at the end of this article LINK.) This is not a jacket you want to go bashing around in. There is a Drishell option for the outer fabric, which increases water resistance and adds 1 oz.

To be fair, the PHD is a bit stingy on down. This gives the garment a bit of a saggy dishrag look. This is not necessarily bad, but it can cause a negative reaction in uninformed consumers. Be assured that the down in the PHD is unrestricted and lofting the maximum amount. The jacket could easily take a few more ounces of down before reaching its maximum chamber capacity.

Note: 0.25 inches of loft per ounce of jacket weight for the Minimus is a considerable achievement. Since shell weight is constant, the less down you use the lower your loft per ounce is. As you add down, your loft-per-ounce ratio goes up significantly with just the addition of a few ounces. This works until you reach the capacity of the shell’s down chambers.

Improvements: Add one or two more ounces of down to the jacket and it could boost its loft to 3.5 or 4.0 inches. This might increase the loft of the jacket to .29 inches per ounce.

Feathered Friends Helios

Feathered Friends Helios 17.3 oz - 4.24 in loft - 0.25 in loft/oz
More Info:

This jacket vied for the honor of having both the greatest loft and highest ratio of loft per ounce. The jacket looks like a million bucks with its puffy Michelin Man chambers. It’s sure to be a winner with consumers. The Helios uses a snug fit and lots of down to achieve high loft and low weight. If you want the basic minimum of features and a body-hugging fit, and you groove on very plump down chambers, this may be the high-performance jacket for you. Meanwhile, this jacket was the most difficult to review. I had some confusion with the size, weight and loft of the jacket.

Size: The Helios, the only size large tested, was smaller than any medium jacket under review, both by measurement and by subjective fit. Everything about the Helios is scaled down. The large Helios had the tightest torso, the shortest arms, the shortest hem, and the smallest pockets of the jackets I examined. The interior pocket opening was so narrow I couldn’t fit my hand inside.

I’m 5’9”, 155 lbs, with a 39 inch chest. I swim in many medium garments, but I found the fit of the large Helios very snug. FF states that “The lighter pieces are cut to be worn in place of sweaters, not over them. If you want a more relaxed fit, choose the next larger size.” Considering this and noting the sizing charts, I conclude I should choose a large for the Helios. Yet in this size, the jacket was far from a relaxed fit. True to its billing, this jacket is not one I would want to put on over anything besides a shirt or base layer. The sleeves were tight and arm movement was a bit restricted by the snug fit, short length, and stiffness from the expanded chambers. The sleeves just covered my wrists. Pulling my hands back into the sleeves wasn’t an option. (The jacket does have insulated hand-warmer pockets.) Fortunately the sleeves have good articulation and raising my arms overhead didn’t lift the hem that much.

Weight: The jacket was also about 1 oz over FF’s specification weight, perhaps a bit more. (Medium is quoted at 15 ounces, so I figure large should be around 16 ounces.) My guess is that most of the extra weight is down fill. I would love to have the person who filled this jacket pouring drinks for me at the bar. This baby is just stuffed with down. The small Helios I examined was overweight as well. Even with custom-made shorter arms, the small weighed more than FF's stated weight for a medium.

Loft: Given the small shell size and amount of down, it isn’t surprising that the Helios achieves over 4 inches of loft with 750+ fill power down. The two Helios jackets I tested, a large and a small, differed significantly in loft. The large measured 4.24 inches and the small 3.49 inches. I have reported 4.24 inches of loft on the accompanying table but be aware that if you have a less generous stuffer at FF, your jacket may be closer to spec. weight and around 3.5 inches in loft. This would equate to around .22 inches of loft per ounce.

My Helios used 1.9 oz Epic for its outer shell and 1.1 oz nylon for an internal lining. FF has since changed to using 1.3 oz taffeta as the standard lining. Except for insulated hand-warmer pockets, the jacket has the basic minimum of features — a non-insulated draft flap for the single- slider front zipper, elastic hem and wrist closures, and a small zippered napoleon pocket on the inside. FF will make you a matching hood if you request and like Nunatak they are a custom shop, so you can get just about any variation you want.

In summary, the Helios is high on performance. It is a very light, high- loft jacket with a minimal set of features. If you like the fit and are fond of very stuffed chambers, this may be just the jacket for you. It will certainly keep you warm.

Improvements: The down chambers on the Helios I tested were very plumply filled. Some of the down’s loft may be wasted by compression in the chambers. Skip the insulated hand warmer pockets and use light fabric for pocket liners. Enlarge the opening on the interior pocket. Change jacket sizing to be more in keeping with that of the rest of the industry, or at least state that your ideal fit for the Helios may be a bit tighter than what many consumers expect, even when purchased a size larger.

Down Jacket Comparison (Table)

  • Download the Down Jacket Comparison Table: Adobe PDF

About Measuring Down Loft

Measuring the loft of a down garment is a difficult thing. Each of the many chambers has a slightly different loft. Measure a jacket once, pick it up and shake it, put it down and measure it again, and you won’t get the same number. Measure it a day later and you’ll get yet another number. All of the jackets increased 10% to 20% in loft over the week of observation. As such, my loft figures are probably as good as you can expect. Under trail conditions where it has been stuffed in your pack all day, you’ll likely have less loft.

I measured each jacket four times over the course of the week. Each time I made ten measurements on a jacket, four on the torso and six on the arms.

A level was used to make loft measurement more accurate.

I took the best two (namely, loftiest) of the measurement sessions for each jacket and averaged them for the loft measurements reported in the comparison table.

The weighted loft figure I report in the comparison table takes into account that torso loft covers more of your body and is more important to overall warmth than sleeve loft. Weighted loft is calculated as follows:

Weighted Loft = [(2 x Torso Loft) + Sleeve Loft] / 3

Thus torso loft gets twice the weight of arm loft in the final loft figure.

Note: Just for amusement, I made the same measurements on my early 90’s Gore-Tex down sweater. It had 3.75 inches of loft, weighed 20.8 ounces and only had .18 inches of loft per ounce. Clearly we’ve come a long way.

About the Microfiber Fabrics

Epic is more water resistant but less breathable than Teijin 30/36. It has a somewhat looser weave and depends on silicone encapsulation to repel water and to close spaces between fibers. After encapsulation, the Epic fabric is very water resistant but not as breathable as untreated microfibers like Teijin 30/36. According to Feathered Friends, Epic is water and wind resistant to 4 lbs/sq. inch. The water resistance is a permanent feature of the Epic fabric and can’t be washed out like a durable water-resistant finish (DWR). Epic is good for light rain, heavily condensing shelters and wet snow. Think of it as a little less waterproof but more breathable than a standard waterproof breathable fabric.

Teijin 30/36 has a very tight weave in both directions and depends on leaving almost no space between the fibers for wind and water resistance. It is more breathable than Epic. A Teijin 30/36 shelled jacket will have less condensation from internal moisture and will dry out faster if damp. According to WM, Teijin 30/36 resists the moisture of mist, fog, dry snow or an inadvertent splash of water — but any greater exposure to moisture and you’ll need a rain shell to protect the jacket. You'd better make sure that your regular rain shell has enough room to fit over a lofty down jacket.

PHD’s M1 is a proprietary fabric. In the absence of any other information, I would guess that the properties of the M1 microfiber fabric are similar to those of Teijin’s 30/36. M1 is probably a lighter fabric than the 1.7 oz 30/36.

The lab will likely do some testing on the water resistance and breathability of these emerging microfiber fabrics in the future.


Thanks to Nunatak Gear for providing the Kobuk Jacket

Thanks to Ellen and Neal Zaslaw for lending me their Helios Jackets.


"Western Mountaineering, Feathered Friends, Nunatak, and PhD Lightweight Down Jackets (Comparison Review)," by Alan Dixon. (ISSN 1537-0364)., 2001-12-16 03:00:00-07.