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Ultralight and ultra lofty.

The Western Mountaineering UltraLite Sleeping Bag lives up to its name by keeping your load manageable while still packing in a hefty dose of premium 850-fill down for those chilly nights. A soft taffeta lining caresses trail-weary skin and, thanks to the Pertex shell's breathability, the climate inside of the bag stays comfortable on balmier nights.

  • Highly breathable, water-resistant Pertex shell protects the down insulation from frost, condensation, and spindrift
  • Packs 16 ounces of ultra-premium, 850-fill down insulation to retain your body’s warmth and maintain a super-high warmth-to-weight ratio
  • Interlocking draft tubes and a down-filled collar prevent energy-sucking drafts from zapping your slumber
  • Slightly narrower shoulder girth helps eliminate pockets of dead air for improved warmth retention
  • Western Mountaineering bags are made in the USA

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Western Mountaineering UltraLite Sleeping Bag: 20 Degree Down

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Here's what others have to say...

Unanswered Question

Will a 6' left zip together with a 5' 6"...

Will a 6' left zip together with a 5' 6" right? If so how does that work? Are the zippers actually the same length and only the tail of the one bag longer? Thanks

4 5

awesome bag

  • Familiarity: I've used it several times

Really great sleeping bag; lightweight and warm for the rating.

Can't decide on the ultralight or the...

Can't decide on the ultralight or the alpinlight. I am skinny - 6-2 150 pounds and am worried the girth of the alpinlight might be too much. However the extra room may be nice for layering and room to move around. Any suggestions?

Responded on

Your worry is well founded. If the bag is too big you will have dead space that needs to be warmed. On the other hand, if you feel like you prefer to layer and have room to move around and can live with the extra space, the the Alpinlite might be a good way to go. Best of luck!

5 5

Excellent & light weight

  • Gender: Male
  • Familiarity: I've put it through the wringer

Really warm for a bag that packs down so small. Weighs almost nothing, but is warm enough for late fall/early winter. Comfy down to -10 C if you wear a wool shirt :-)

5 5

Amazing Bag- Bag For Life

  • Gender: Male
  • Familiarity: I've used it several times

I first bought the HighLite 35 degree bag, slept out in New York in November and was a bit cold, so I returned it and got the UltraLite. The bag is incredible- super warm, great construction, packs down very small. Expensive, but I expect it will last for decades.

5 5

Like it but may be too small

  • Gender: Male
  • Familiarity: I've used it once or twice and have initial impressions

I bought the Ultralite and the Alpinlite to see which fit me better. Both bags are very well made and both are the long (6'6") size. The stitching is perfect, the zippers work great without snagging although I am careful with them just to be safe. The problem for me is determining which one to keep. I think this is a fairly common occurrence, so I thought I?d try to provide some information for anyone trying to make the decision.

I think I've read every article on the internet about both bags and am really sold on staying with WM. I'm 6'1.5" and fluctuate between 170 and 180 lbs. My chest measurement is 42.

It seems like the Ultralite's shoulders are fine at 60"but the hip measurement feels fairly tight. I think the foot measurement is fine, although I can notice the inch difference on the Alpinlite in that area.
As far as the Alpinelite...I really like the foot measurement of 39". I also like the hip measurement of 56" a lot more that the Ultralite's 52". It doesn't seem like a lot, but it is to me. I'm mostly a side sleeper in case you were wondering. The Alpinlite?s should measurement is what makes me wonder which one to keep. It?s really large at 65?. There is considerable difference between the two and it?s almost as if I need the Alpinlite?s hip and foot measurements with the Ultralite?s shoulder measurements. The bags are so similar with respect to function, that it doesn?t make sense to keep both. I may end up keeping the Alpinlite because I flop around a lot at night. The perfect WM bag for me would be a 20 degree bag with the following measurements ? 60-62?shoulder, 56? hip, 39? foot.
I give the bag 5 starts because the fit and finish is immaculate and everything works as it should.
One more note - If you are over 6 feet tall go ahead and get the long. It will be perfect once you extend your toes.

I am 5'7 could i fit into the 5'6 bag or...

I am 5'7 could i fit into the 5'6 bag or should i just go with a 6 and put some clothing at the bottom to fill in the gap?

Best Answer Responded on

Go with the 6'. If you are too big for a bag, you will over-compress the insulation and lower the temp rating.

I'm a petite female looking for my first...

I'm a petite female looking for my first down bag after borrowing a friends' and loving it.
I swore I'd never camp again with temps under 25 degrees with my current bag.... would the ultralight be warm in temps down to 15? What temp bag should I actually be looking for? These temp ratings can be confusing!
I'm like a lot of women...cold feet, hands, cold everything....
I'm also interested in a bag that packs light and small..this thing goes with me on my bike, suitcase, and whatever couch I might be crashing on....
Thanks for any advice!

Responded on

If you cold take the warmes sleepingbag you can take.
The EN rating is what you lokking for. it said women r cold and need a warmer bags...dont go by the US raiting, you get cold
I hope it's help (:

Responded on

Disregard what Guy said--EN ratings are good for comparing different brands of bags but don't give you an accurate temperature that you'll be comfortable in.

Western bags are over filled and conservatively rated. I have slept in a 25degree Western sleeping bag in 25degree weather and I was perfectly warm and I get cold easily. The key is the amount of down put into the bag. Not only does Western use the highest quality European goose down they can get, they then put large amounts of it in the bags.

I'd trust the temperature rating with Western Mountaineering bags. The average person would be warm 5 degree below the rating, but if you are thinking you'll regularly experience below 20 degrees AND you run cold, I'd think about the Versalite for a couple ounces more. You could also get a sleeping bag liner that would boost the temp rating on the trips you think temps would be colder than 20.

Hope this helps...

Responded on

As far as EN ratings go- I have never, ever found any sleeping bags that have met of exceeded WM's in accuracy. WM has never let me down and cost me a single night's sleep because I was cold....the only problem is not wanting to get up in the morning.

Responded on

Western mountaineering bags are indeed conservatively rated. If you look at a UK site, you'll get the EN ratings (EN is required in europe I believe). Over in the EU the Ultralite is billed as a 16F bag rather than a 20F as in the States. I think they refrain from quoting the EN rating because they have built a decades long brand on their old conservative ratings and want to maintain reliability from year to year over marketing hype (even if it is in their favor).

Why is there no Left Zip option for the...

Why is there no Left Zip option for the 6ft bag?

Responded on

When Backcountry runs out of a certain item, it disappears from the purchase options. Left zip is available, but Backcountry doesn't have any right now.

im looking for a bag to use on my thru-hike...

im looking for a bag to use on my thru-hike next year on the PCT, and its a toss up between this and the apache. is the couple ounces of weight worth sacrificing the durability of a regular WM bag?

Responded on

Having used Pertex in both bags and jackets for a while now, I can tell you that durability shouldn't be a concern. Unless you intentionally pull your bag through thorny bushes or slide down abrasive rocks using the bag as a sled, you'll be fine.

Between the two bags, I'd be more concerned about fill weight. You get an extra 3oz of down in the Apache. That could make a huge difference on the PCT. If you decide to go with the UltraLite, call WM and ask them about having it overstuffed. Then, you can get the benefits of more down and keep the light weight.

5 5

Took the big leap

I've spent my career working in large wilderness areas in MT and WY. I've have NEVER been a fan of down gear and 99.9% of cold weather gear I own is synthetic insulation. Believe me, I've been spanked by Pa nature far too many times in the backcountry to take the lessons learned lightly. However, my main backpacking, ski, and inflatable kayaking buddy has owned one of these WM bags for YEARS of constant use. I on the other hand have gotten by very well on NOLS garage sale MH used synthetic bags and a MH lamina(?) -40 bag for winter. (as an aside, I will NEVER own another synthetic bag made by the furry rodent people, not good). I still have my 1969 Outward Bound REI McKinley down bag that has outlived it's usefulness (lack of ventilation and loft, i.e. cold spots). However, since my retirement goals in 20 months are to start ticking the long distance trails, I've been retooling my gear for as light weight and quality. Knowing how pleased Curt has been and researching the rep on these bags finally caused me to reluctantly shell out the big buck...(on sale). I am extremely pleased with this top quality made purchase. So far so good, and am confident in the long run that it will perform as well as it has for Curt and the other reviewers have raved.

I have a Marmot Pinnacle, and the regular...

I have a Marmot Pinnacle, and the regular size is just right for me. Anybody know how comparable the Ultra compares, size-wise?

Best Answer Responded on

These bags are made to fit their size. So a 6' bag fits a 6' person. If you are right at 6', you'll fit just fine in this bag.

5 5

Light weight and warm

So far, I have had the bag out for two trips and it has performed very well. The lightness and compact size of the bag help me cut down on pack weight and size. It sleeps very comfortably and I can't wait to get it out in some colder weather.

Light weight and warm
5 5

Changed the game

My old bag was a Marmot Sawtooth 15. That bag got great reviews and was warm enough I guess, but it just didn't compare to the WM UltraLite. The Marmot weighed nearly twice as much as this thing. This bag has brought my base weight down to under 8lbs, and I can absolutely notice a difference. I don't even have to use my hip belt on shorter trips, my bag is so light now.

Other than weight, another great thing about Western Mountaineering is that their temperature ratings seem to be very accurate. I had used my Marmot bag in 20 degree weather before and was uncomfortably chilly in the morning. It got to about 25 where I was this past weekend and I was still extremely toasty, leaving me no doubt that this bag will go to at least its rated temp, if not even lower without problems.

3 5

Not for the money...

This is a light bag. It is warm (I found the rating to be a little optimistic). My biggest complaint (and why I got rid of mine) was that the material is not nearly down-proof enough: I was always loosing feathers or being poked by feathers. If you want the best US-made, lightweight down bag that doesn't spear you during your slumber, check out Feathered Friends - hand made in Seattle.

Responded on

After 200+ nights of sleeping in this bag, I can honestly say I never witnessed the loss of a single feather.

Responded on

note from Gary at Western Mountaineering: If your bag leaks down through the fabric I would recommend sending it back to us for evaluation. It may be covered under warranty and we may decide to replace it but need to see it first. Some down may migrate through the material occasionally, especially if a compression sack is used, but if there are more than 7 or 8 places where down is poking through the fabric then I recommend contacting us or sending it back for evaluation.

5 5

Can a bag be any better

Switched over to this bags several years ago an have carried for over 1000 miles. Will not get another bag. Super light weight and very warm and it can be packed smaller than a 32oz water bottle.

Responded on

Just because it can pack down that small doesn't mean it should. You are likely damaging the down and/or baffles of the bag. Just a friendly warning.

Is the ripstop shell on this bag water...

Is the ripstop shell on this bag water resistant or repellent? And is there any moisture-wicking property to the lining?

Best Answer Responded on

The "Pertex" shell offers slight water resistance but not enough to rely on more than normal condensation build-up & the inner lining doesn't wick but does breathe. This is from the manufacturer: "These bags are designed for special applications where compressed volume and weight are critical factors. Although some durability is sacrificed with these lighter fabrics, our ExtremeLite™ bags are perfect for the lightweight specialist."

5 5


I Recently took my Western Mountaineering UltraLite 20 degree bag on an early season AT thru-hike. I combined it with a silk liner and slept comfortablly with tempature droping into the teens. When tempatures dropped into the singles and below zero I had to add my space blanket to the mix. It compressed very nice and quickly regained it loft once out of my pack. The full zipper allowed me to use it as a quilt when tempatures warmed up, and the mummy style allowed me to cinche up and trap body heat when it got cold.

The Western Mountaineering UltraLite 20 degree is one of the best bags out there...!!!!

Responded on

I don't use a compression bag for my sleeping bag when I hike. This allows me to pack more efficiently and once out of my pack my bag seems to regain it loft quicker. It also saves a little bit of weight...

Responded on

I think a Western Mountaineering Hot Sack is a much better option than the space blanket. But there is a trick to using it. Once inside your body can't self regulate temperature by perspiring. So you may overheat and sweat until wet. The trick is to only be inside of part of the bag when warm, e.g. move it down from your neck to your waist, or to you knees when warm. Then you will still be warm, but won't sweat inside the Hot Sack. I think the Hot Sack is an amazing way to add the ability to do more cold with less weight!