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Hands-on Gear Review

Western Mountaineering UltraLite Review

Western Mountaineering UltraLite
Top Pick Award
Price:   $500 List | $484.95 at Backcountry
Compare prices at 4 resellers
Pros:  Warmest bag in our review, lightweight, great no catch zipper design, excellent compressed size
Cons:  Expensive, very warm for mid-summer, weak velcro closure for draft collar, slightly on the tight side dimensionally
Bottom line:  This is the warmest 20F we have tested while remaining one of the lighter and more compact models in our review.
Editors' Rating:     
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Manufacturer:   Western Mountaineering

Our Verdict

An excellent 3-season backpacking sleeping bag that borders on the ability to use in some 4-season applications, the Western Mountaineering UltraLite is best suited for colder sleepers or mid to high elevations during the middle of summer, and is warm enough to take along on late spring or early fall trips in the mountains. The other Western Mountaineering bag we tested in this review, the MegaLite, offers more internal space and being on the warmer side of 30 F bags, is plenty warm enough for almost all 3-season applications. As a result of having less insulation, it is lighter and able to compress to a smaller size.

That's not to say that the UltraLite isn't a fantastic bag, especially for those who want a warmer option than the MegaLite offers. The UltraLite is slightly narrower than the MegaLite; however, even tester Ian Nicholson, a self-admitted broad-shouldered backpacker, didn't mind the slimmer cut of the UltraLite, even while wearing a jacket. If you're a bigger person, and you want a little more space or plan on wearing a down jacket to bed on a regular basis, consider the wider Western Mountaineering AlpinLite.

As with other Western Mountaineering bags, we like that it is made in the U.S.A., uses ethically harvested down and has simple, functional features.


RELATED REVIEW: The Best Men's Backpacking Sleeping Bags of 2017

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Score Product Price Our Take
95
$470
Editors' Choice Award
If we could only have one bag this would be it, as it's nearly the lightest and most packable model that offers spacious dimensions and above average warmth.
94
$459
Top Pick Award
One of the best overall sleeping bags on the market for its weight, warmth, and compressed size.
91
$500
Top Pick Award
This is the warmest 20F we have tested while remaining one of the lighter and more compact models in our review.
88
$469
Top Pick Award
If weight and packed volume are your biggest priorities, then look no further.
85
$220
Top Pick Award
One of the most comfortable models; it's compressible enough for week long backpacking adventures.
85
$400
This bag is high performing and is made with quality materials; it remains a high scorer across the board.
81
$270
Best Buy Award
A solid sleeping bag that is close in weight and compressed size to many bags that are sometimes double the price.
81
$240
Top Pick Award
The best 20F synthetic sleeping bag for weight and compressibility.
78
$220
The lightest 35F synthetic bag we know of; it's 3 ounces lighter than the 20F Hyper Cat, though the Spark is significantly more compressible.
76
$170
While hardly high-performance, the Cat's Meow remains a jack-of-all trades for general purpose backpacking, car camping, extended kayaking trips or when extended poor weather is a possibility.
76
$300
A super unique design that brings unparalleled comfort to the backcountry albeit with some (though not terrible) weight and packed volume penalties.
74
$160
Best Buy Award
For budget conscious backpackers looking for a long lasting down bag, look no further.
65
$90
Likely the best 20F bag that costs less than $100.

Our Analysis and Hands-on Test Results

Review by:
Ian Nicholson
Review Editor
OutdoorGearLab

Last Updated:
Thursday
March 23, 2017

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Performance Comparison


Check out the Overall Performance chart to see how the Western Mountaineering UltraLite ranked amongst the competition.


The US-made WM Ultralite was the warmest sleeping bag in our review and also among the most compressible  lightest weight  and offering the "coziest" internal fabric.
The US-made WM Ultralite was the warmest sleeping bag in our review and also among the most compressible, lightest weight, and offering the "coziest" internal fabric.

Warmth


The 20 degree Fahrenheit rating of the UltraLite is pretty conservative. It is certainly on the warmer side of the 20F bags available and is the warmest bag in our review. We slept in a 14F night with long underwear and a light fleece and were super comfortable when the draft collar and hood were properly cinched.


While we appreciate the extra space to roll around in or comfortably throw a thick jacket on while using the bag, which can be found in the The North Face Cats Meow and Kelty Cosmic Down, and to a lesser extent, the Marmot Phase. The UltraLite is a much more thermally efficient sleeping bag for average sized, or still even slightly larger than normal users. Remember that fit is a crucial component of a warm sleeping bag. The wider, "more-comfortable" bags have more dead air space inside the bag, resulting in a better chance for cold spots and the possibility of disrupted sleep.

The WM Ultralite was hands down the warmest bag in our review. Our testers even used this bag down to 14° without having to add that many layers and slept very comfortably.
The WM Ultralite was hands down the warmest bag in our review. Our testers even used this bag down to 14 without having to add that many layers and slept very comfortably.

Similar to the MegaLite, the UltraLite features continuous horizontal baffles. This design allows you to shift down from the top of the bag to the bottom of the bag, or vice versa. This is a very functional way to control the temperature inside your bag; you can have more insulation on the top of the bag for cold nights and the opportunity to shift that down to the bottom, where it can be compressed (and less useful for keeping you warm on those hotter nights).

Very inviting lofty down and soft  lightweight 12D Extremelite fabric featured on the outside of the WM UltraLite. The fabric used on the inside of the UltraLite (and MegaLite) was our testers favorite for feeling the "coziest" and softest against our skin.
Very inviting lofty down and soft, lightweight 12D Extremelite fabric featured on the outside of the WM UltraLite. The fabric used on the inside of the UltraLite (and MegaLite) was our testers favorite for feeling the "coziest" and softest against our skin.

Weight


The regular length UltraLite weighs 1 lb 13 oz. It's nearly the lightest bag that is rated to a temperature of below 25F (in our review) and is lighter than a majority of bags rated in the 30-35F range (that are currently on the market). The exception is the Marmot Phase 20 which isn't quite as warm as the UltraLite but warmer than most other 20 F bags and is more compressible and an amazing 6 ounces lighter checking in at 1 lbs 7 ounces and is one of the better performing all-around bags in our review. Be sure to check out the chart below to compare the weight score of the UltraLite to the other bags in this review.


What's more amazing about the weight of the UltraLite is not only is it warmer than a majority of 20 and 25 bags we reviewed, but in several cases, it was significantly warmer than these models.

At 1 lbs 13 oz  the UltraLite remains among the lightest bags in our review  and for cold sleepers or early season trips the UltraLite is more than reasonably weighted for even the most extended outings. Photo: The WM UltraLite out for an extended early season trip in the High Sierra.
At 1 lbs 13 oz, the UltraLite remains among the lightest bags in our review, and for cold sleepers or early season trips the UltraLite is more than reasonably weighted for even the most extended outings. Photo: The WM UltraLite out for an extended early season trip in the High Sierra.

The UltraLite uses "Extremelite", a 12D fabric for the shell, and is the exact same as our award winner, the Western Mountaineering MegaLite. Extremelite fabric weighs less than 1 oz per square yard, which is insanely light. The ultra-fine yarn that makes up this fabric is very soft and ultra-compressible. Albeit a little bit fragile, this very down-proof fabric greatly contributes to the bag's low weight and high compressibility. Another contributing factor to the low weight of the UltraLite is its slim cut, which is indeed one of the narrower sleeping bags in our test. Less material obviously shaves a handful of ounces from the overall weight.

The dimensions of the WM UltraLite are a little slimmer than several bags we tested. Here  the Ultralite (center) compared to the WM MegaLite (left) and the 20F Kelty Cosmic Down (right).
The dimensions of the WM UltraLite are a little slimmer than several bags we tested. Here, the Ultralite (center) compared to the WM MegaLite (left) and the 20F Kelty Cosmic Down (right).

Comfort and Fit


High loft and soft, lightweight materials make the UltraLite a very inviting place to lay your head for the night, earning it an 8 out of 10 in this metric. However, the narrow shoulder and hip girth make it less comfortable than the MegaLite, Marmot Phase 20, Patagonia 850 Down 30, The North Face Hyper Cat, Nemo Salsa 30, or Sierra Designs Backcountry Bed 600 3-Season. Folks who mostly sleep on their back won't detect this as much, but for side and tummy sleepers, it is more likely to be noticed. Overall, the UltraLite and MegaLite offered the softest and most comfortable feeling face fabric out of all the bags that we tested. It is worth noting that the Marmot Phase offers slightly larger dimensions and feels slightly wider than the UltraLite.


The Kelty Cosmic Down, Sierra Designs Backcountry Bed 600, and Nemo Salsa 30 are reasonably priced contenders that scored a 9, 10, and 10, respectively, in the comfort metric. If you're looking for an option that offers quality and comfort at a cheaper price point, consider these bags.

The WM Ultralite pictured in its included stuff sack. This stuff sack worked okay  but we could easily pack the UltraLite a 1/3 smaller with a compression sack.
The WM Ultralite pictured in its included stuff sack. This stuff sack worked okay, but we could easily pack the UltraLite a 1/3 smaller with a compression sack.

Packed Size


Five inches of loft looks like a lot to pack away when this bag is laid out on your sleeping pad. However, the 850+ fill down and extremely light weight materials make the UltraLite a much smaller package than you would expect, especially when stuffed into its included well-fitting stuff sack - or better yet, a compression sack.


The WM Ultralite (third from the left) offered one of the smaller packed sizes among any bag we tested  something that was particularly impressive because it was also the warmest bag we tested.
The WM Ultralite (third from the left) offered one of the smaller packed sizes among any bag we tested, something that was particularly impressive because it was also the warmest bag we tested.

Despite being the warmest bag in our review, it was among the most compressible and packed down WAY smaller than all the 20F bags (and most of the 30F bags). The only bags that packed smaller were the Western Mountaineering MegaLite, Marmot Phase and Sea to Summit Spark Spark III.

The included oversized storage sack for the WM Ultralite. This cotton bag was perfect for long term storage and helping to keep your bag lofty and performing well for years to come.
The included oversized storage sack for the WM Ultralite. This cotton bag was perfect for long term storage and helping to keep your bag lofty and performing well for years to come.

Features and Design


The continuous horizontal baffles on the UltraLite make for an easy-to-use thermostat. The down chambers encircle the sleeping bag from zipper to zipper, allowing the user to shift down towards the top of the bag for cold nights. Conversely, you can shift the material beneath the bag for warm nights. By opening the bag and laying it flat, you can press down and run your hands in the desired direction, pushing insulation to where you need it more or less.


The above chart details each bag's score in the Features and Design metric.

The well-designed reverse differential hood on the WM Ultralite. Basically  the fabric on the inside of the sleeping bag is actually larger than the shell fabric resulting in a very comfortable and effective fit without needing to tighten it too much.
The well-designed reverse differential hood on the WM Ultralite. Basically, the fabric on the inside of the sleeping bag is actually larger than the shell fabric resulting in a very comfortable and effective fit without needing to tighten it too much.

Similar to the AlpinLite, the UltraLite features a reverse differential hood, which is extremely comfortable. This basically means the fabric on the inside of the sleeping bag is actually larger than the shell fabric. This hood covers your head, offering extreme comfort, and is excellent at trapping heat without needing to tighten it too much.

The WM Ultralite features a one-inch wide stiffening tape on both sides of the zipper that helps to aid in easy  snag-free operation.
The WM Ultralite features a one-inch wide stiffening tape on both sides of the zipper that helps to aid in easy, snag-free operation.

Western Mountaineering uses a one-inch stiffening tape on both sides of the zippers that aids in easy, snag free operation. The draft tube along the zipper, and the draft collar on the UltraLite are lofty; they mate well, which keeps the warm air in, and cold air out. However, Western Mountaineering should consider a different method for closing the draft collar and the hood of this sleeping bag. Both closures are small pieces of velcro that are hard to spot and operate and come open very easily in the night. The draft collar, in particular, allows a minimal amount of cold air to enter the bag.

While there is a pretty big range in denier thickness among bags we tested  we didn't think that it greatly affected a bags durability  as sleeping bags (hopefully) aren't exposed to too many sharp objects or abrasions. Conversely  a lighter weight 10-12D shell fabric can weigh only a third of an average-weight bag using a 30-50D shell.
While there is a pretty big range in denier thickness among bags we tested, we didn't think that it greatly affected a bags durability, as sleeping bags (hopefully) aren't exposed to too many sharp objects or abrasions. Conversely, a lighter weight 10-12D shell fabric can weigh only a third of an average-weight bag using a 30-50D shell.

Versatility


The UltraLite is likely the most versatile bag in our review. It's capable of unzipping for warmer nights, but can be used in temperatures of 20F, as rated (and when sealed up). For sleepers that experience the cold sooner than others, or on extra cold nights, nearly all of our testers had no problem adding at least one lighter weight jacket to boost this bag's warmth (if temps really got frigid). The continuous baffle design also lets the user further regulate temperature. The bottom line is even for the weight-conscious backpacker, this one pound thirteen ounce sleeping bag is very reasonable to carry and is certainly warm enough for the cold nights of the shoulder seasons or at higher elevations.


The North Face Cats Meow and Nemo Salsa 30 are two contenders that also scored 10 out of 10s for versatility. The Cats Meow excels on shorter backpacking trips, extended car camping trips, or adventures where you might expect to feel a bit of moisture. The Salsa works for those fast and light backpacking trips, but is also comfortable enough to be used on extended car camping trips, especially as it ensures that the sleeper has adequate space to move around in.

The WM UltraLite is a very versatile bag  performing well on both warm summer nights to shoulder-season alpine forays. Here we stayed cozy in the Western Mountaineering UltraLite even during a very cold late season rainstorm.
The WM UltraLite is a very versatile bag, performing well on both warm summer nights to shoulder-season alpine forays. Here we stayed cozy in the Western Mountaineering UltraLite even during a very cold late season rainstorm.

Best Application


The UltraLite is the one of the best sleeping bags in our review for 3-season use. Because it's so warm, it's best suited for travel in the mid to high elevations in the middle of the summer. It is also warm enough to stretch your season into the shorter days of fall and transitional periods in the spring. If you're someone who gets cold easily, the UltraLite could be your anytime, anywhere 3-season bag. It's plenty warm for most summer-time mountaineering in the lower-48 and lower regions of Canada and is light and compact enough for spring multi-day ski touring missions.

At $500  the WM Ultralite is on the more expensive side  but we still think its a good value if you can afford the initial investment. This made-in-the-USA sleeping bag (with the sewers names labeled here) uses the highest quality materials and craftsmanship and will easily last 15  20  or more years and will perform well on an extremely wide range of trips.
At $500, the WM Ultralite is on the more expensive side, but we still think its a good value if you can afford the initial investment. This made-in-the-USA sleeping bag (with the sewers names labeled here) uses the highest quality materials and craftsmanship and will easily last 15, 20, or more years and will perform well on an extremely wide range of trips.

Value


One of the reasons that we prefer high-quality down sleeping bags is that they have a very long lifespan if they are well taken care of. Unlike synthetic fabrics, they can be stuffed and unstuffed over and over without breaking down the insulation. If you are able to buy a quality bag that can handle most, if not all, of your on trail (or off trail) adventures, you will save some cash in the long run.

However, at around $500 for the regular length model, the UltraLite is a pretty big investment. But, if that bag can sustain 10-20+ years of use, and be your go-to for most of your backpacking trips, along with maybe the occasional mountaineering or ski touring adventure, we think that it is a good investment. You won't be disappointed by the UltraLite. If considering the Ultralite be sure to check out the similarly performing Marmot Phase 20 which is $40 less expensive.

The WM Ultralite is a former Editors' Choice and remains a fantastic and versatile bag. The only reason it didn't win our overall Editors' Choice is that it's a little warmer than most people need for backpacking  and the MegaLite featuring less insulation compresses smaller and is 5-ounces lighter. However  for cold sleepers or colder than average conditions the UltraLite is tough to beat.
The WM Ultralite is a former Editors' Choice and remains a fantastic and versatile bag. The only reason it didn't win our overall Editors' Choice is that it's a little warmer than most people need for backpacking, and the MegaLite featuring less insulation compresses smaller and is 5-ounces lighter. However, for cold sleepers or colder than average conditions the UltraLite is tough to beat.

Bottom Line


The UltraLite is a former Editors' Choice and remains a fantastic bag. It offers a few disadvantages, mostly revolving its slimmer-than-average fit, but is among the lightest, warmest, and most compressible bags for its temperature rating, similar to the Marmot Phase. The UltraLite wins our Top Pick for the Best 3-season sleeping bag for cold sleepers or "colder" 3-season use, as it is still noticeably warmer than the Phase. The MegaLite won our Editors' Choice over the UltraLite because it is a little more spacious; it also offers a 30F rating that we think is warm enough and more appealing for most folks that are interested in backpacking bags. As a result of having less insulation, the MegaLite compresses smaller and is five ounces lighter. If you're a cold sleeper, the UltraLite is tough to beat for weight, packed size, comfort of materials, and warmth.
Ian Nicholson

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