The world's most in-depth and scientific reviews of gear

Best Ultralight Sleeping Bags of 2021

Waking up to a chilly morning after sleeping out in the San Juan Mount...
Tuesday May 4, 2021
  • Share this article:
Our Editors independently research, test, and rate the best products. We only make money if you purchase a product through our links, and we never accept free products from manufacturers. Learn more

Over the last 10 years, we have bought and tested over 42 different ultralight sleeping bags. Our 2021 review compares 15 of the best models. Our team of fast packers, climbers, and thru-hikers spent countless nights testing these bags across the world. From blustery mountain passes to hidden desert canyons, from the Himalayan Mountains to the Colorado Plateau, we carried these bags for miles and miles. We also put them through controlled temperature testing. No matter if this is your first foray into the ultralight world or you're an old hat looking to update your gear, we're here to help you find the perfect bag for your ultralight adventures.

Related: Best Ultralight Tent of 2021

Top 15 Product Ratings

Displaying 1 - 5 of 15
< Previous | Compare | Next >
 
Awards Editors' Choice Award Best Buy Award Editors' Choice Award   
Price $364 List$300 List$410 List$379 List$359.00 at Feathered Friends
Overall Score Sort Icon
73
72
71
70
68
Star Rating
  • 1
  • 2
  • 3
  • 4
  • 5
  • 1
  • 2
  • 3
  • 4
  • 5
  • 1
  • 2
  • 3
  • 4
  • 5
  • 1
  • 2
  • 3
  • 4
  • 5
  • 1
  • 2
  • 3
  • 4
  • 5
Pros Highest scoring ultralight sleeping bag, best features, and most versatileVery affordable, highly customizable, versatile, lots of featuresWarmth-to-weight ratio, excellent fabric, best bag with a hood, versatileWarm for an ultralight bag, simple and versatile design, box baffle construction, waterproof stuff sackSuper simple and light, highest quality down, spacious and comfortable
Cons Not as warm as others (in the version we tested), neck draw cords loosen over timeLong wait for product to be custom made and shipped, foot box draw cord still leaves a little hole, lots of buttons and strapsTight fit, shallow hood, expensiveA little constricting, small foot box, not the best neck draw cord designNo zipper, hard to tell the difference between variable fill zones, must be paired with warm jacket, feet can get hot in warmer weather, not as versatile as other ultralight bags
Bottom Line The best performing set of features that allow for the most versatile usageThe warmest quilt in our review also comes at a reasonable priceA very warm and lightweight full mummy with a full zipWith an enclosed foot box and ¾ length zipper, this warm hoodless mummy can also be used quilt styleThe only mummy bag that uses more down fill in the foot box and less around the torso, to take advantage of the clothing you have with you
Rating Categories Flicker 40 UL Revelation 20 Summerlite ZPacks Classic Feathered Friends Vireo UL
Warmth (30%)
7
9
9
9
8
Weight (25%)
5
5
5
5
7
Comfort (20%)
7
6
6
6
8
Versatility (15%)
10
8
8
9
4
Features (10%)
10
8
7
5
4
Specs Flicker 40 UL Revelation 20 Summerlite ZPacks Classic Feathered Friends...
Style Center zip mummy bag or unzipper to be quilt Quilt Hooded mummy Hoodless mummy Hoodless, zipperless mummy
Manufacturer Stated Temperature Rating 40F 20F 32F 20F 25F lower half, 45F upper half
Measured weight, bag only (ounces) 19.1 oz 20.9 oz 19 oz 20.3 oz 16.4 oz
Claimed weight from manufacturer (ounces) 20 oz 20.19 oz 19 oz 19.8 oz 16.7 oz
Stuff Sack Weight (ounces) 0.8 oz 0.6 oz 1 oz 0.9 oz 0.8 oz
Stuffed Size 7" x 10" 7" x 12" 6" x 12" 6" x 12" 7" x 10"
Fill Weight 8.4 oz 13 oz 10 oz 13.1 oz 9.4 oz
Fill Power 950+ goose down 850 Downtek 850+ goose down 900 fill 950+ goose down
Construction Continuous baffles U shaped baffled quilt Continuous baffle Vertical upper baffles and horizontal lower baffles, box baffle construction No hood, no zipper and a variable fill
Shell Material Pertex Endurance UL 10D nylon fabric 100% nylon ripstop .70 oz/sqyd (23.7 g/m2) Ventum Ripstop Nylon w/ DWR Pertex Endurance UL
Shoulder Girth (inches) 62" 55" 59" 61" 64"
Hip Girth (inches) 48" 55" 51" 61" 48"
Foot Girth (inches) 39" 55" 38" 35" 38"
Zipper Length Full length center zip 1/3 length at bottom Full length 3/4 length No zipper
Sizes Regular, long, and wide Short/regular, regular/regular, regular/wide/ long/wide 5'6", 6', and 6'6" Slim, standard, and broad (girth) short, medium, long, x-long and xx-long (length) 62", 68", and 74"
Temp Options (degrees Fahrenheit) 20, 30, 40F 10, 20, 30, 40F 32F 10, 20, 30, 40F 25, 45F

Best Overall


Feathered Friends Flicker 40 UL


Feathered Friends Flicker 40 UL
Editors' Choice Award

$399.00
at Feathered Friends
See It

73
OVERALL
SCORE
  • Warmth - 30% 7
  • Weight - 25% 5
  • Comfort - 20% 7
  • Versatility - 15% 10
  • Features - 10% 10
Weight: 19.1 oz | Fill: 950+FP Goose Down
Super high fill power down
Functions as a quilt or a mummy bag
Full-length zipper with baffle gives you complete enclosure
No hood
Expensive
Not quite as light as the lightest bags available

Due in large part to its incredible versatility, the Feathered Friends Flicker 40 UL is yet again the highest-rated model in this review. Whether you are trying to ventilate on a hot night or bundle up when the temperature drops, this bag has you covered. It is fitted with a full-length zipper down the center, which allows it to be used as both a hoodless mummy bag or a flat quilt, giving you the best of both worlds. The Flicker 40 pairs super high loft, 950+ fill power down with a shell made of water-resistant and breathable Pertex Endurance UL. Feathered Friends spared no expense and used only the very best and lightest materials in this masterpiece.

This is not the warmest bag--we opted to test the 40F version to try out the lightest Flicker available, and it kept us warm in that temperature range, but any colder, and we weren't exactly toasty. Check out the 30F and 20F options if you want extra warmth for a bit more weight. The lack of a hood also reduces the warmth on cooler evenings. We like the dual drawcords at both the head and feet, which lets you wear it around camp on chilly mornings, and the full-length zipper is far higher quality and more functional than the weight-saving buckle and strap systems used on some competing quilts. The Flicker is the clear winner of this comparative review, and we happily recommend you start your search for an ultralight sleeping bag by checking out this model.

Read review: Feathered Friends Flicker 40 UL

The Best Ultralight Hooded Mummy Bag


Western Mountaineering Summerlite


Western Mountaineering Summerlite
Editors' Choice Award

$440.00
at Backcountry
See It

71
OVERALL
SCORE
  • Warmth - 30% 9
  • Weight - 25% 5
  • Comfort - 20% 6
  • Versatility - 15% 8
  • Features - 10% 7
Weight: 19 oz | Fill: 850 Fill-Power Down
A fully enclosed mummy bag with hood
Really warm and thermally efficient
Lightweight for a full-zip hooded mummy
Tight cut
Shallow hood
Pricey

When something works well, we don't see a good reason to change it. The Western Mountaineering Summerlite has been around a while and is a stalwart ultralight bag for a lot of good reasons. Although it isn't EN rated, it seems appropriately warm for its 32F rating bolstering our belief that Western Mountaineering's approach to temperature ratings tends to be a lot more conservative than others. The Summerlite sandwiches high-quality 850 fill-power down between 12-denier fabric coated in a robust DWR to make a toasty package for a good night's sleep. Despite the full-length zipper and hood, the Summerlite comes in at a competitive weight of 19 ounces. It's lighter or as light as most of the quilts in this category, too, while also staying pretty versatile.

The one sacrifice it does make is a tighter cut, especially at the legs, so this may not be a great choice for larger folks or more restless sleepers. Because it's a regular mummy, it's less dependent on matching it with a specific pad, so it can be used whether you're stretching out in a hut along the Appalachian Trail or curled up on a frozen sloping ledge on the side of a mountain. The Summerlite is our favorite full mummy bag for ultralight uses.

Read review: Western Mountaineering Summerlite

Quilts vs. Mummy Bags
We know, we know: quilts versus mummy bags can be a polarizing topic. We believe there are excellent arguments on both sides of this issue and therefore, we chose a favorite bag for each type. Some of our testers prefer quilts, some prefer mummies, and that's just fine. We set out on this review to provide info to both schools of thought. Our only firm conclusion is that your needs supersede anyone else's opinion on the matter.

Best Bang for the Buck


Enlightened Equipment Revelation 20


Enlightened Equipment Revelation 20
Best Buy Award

$300 List
List Price
See It

72
OVERALL
SCORE
  • Warmth - 30% 9
  • Weight - 25% 5
  • Comfort - 20% 6
  • Versatility - 15% 8
  • Features - 10% 8
Weight: 20.9 oz | Fill: 850 Fill-Power Down
Great value
Warm for a quilt
Lofty 850 fill power, hydrophobic down
Lots of customizable options
Constrictive when fully buckled up
Long, dangly drawcords

For many people, the weight-to-warmth ratio isn't the only consideration when it comes to ultralight gear. Price is also important. We think that the best balance of the two might be the Enlightened Equipment Revelation 20. It didn't score quite as high as the Feathered Friends Flicker, but it's available for a nice chunk less, with the added benefit of free shipping in the USA. It's hard to find a bag as versatile and warm as this one. The quilt can be opened up into a blanket for summer nights, or sealed down around a sleeping pad for maximum warmth. The Revelation is customizable in about every way, from fill power, fabric weight, overall width and length, and even colors. We tested the "stock" model for this review — beware that a customized quilt can take 2-4 weeks for delivery, but with a plethora of options, you can really dial this one in to meet your specific desires.

If you're close to the limits of the dimensions of the quilt, we recommend sizing up, as our larger testers found the quilt a bit constricting when entirely closed up. The attachment system, while very adjustable, is a bit dangly, which we occasionally found annoying. However, the current model is the warmest quilt we tested and quite comfortable across a wide range of temperatures so it scored well in our tests. For a great quilt with a justified price, the Revelation is a worthy contender.

Read review: Enlightened Equipment Revelation 20

Best for a Tight Budget


Hammock Gear Burrow Econ 20


Hammock Gear Burrow Econ 20
Best Buy Award

$180 List
List Price
See It

60
OVERALL
SCORE
  • Warmth - 30% 6
  • Weight - 25% 3
  • Comfort - 20% 7
  • Versatility - 15% 8
  • Features - 10% 8
Weight: 25 ounces | Fill: 800 Fill-Power Duck Down
Bargain for what you get
Decent versatility
Customizable
Not that warm
Doesn't cinch as well as some

For some ultralight backpackers, spending more can be worth it to trim a few ounces. The Econ line from Hammock Gear, however, proves that you don't need to break the bank for a quality lightweight quilt. We tested the Econ Burrow 20, and we were surprised at how well it performed despite a price that was less than half the cost of some of the premium models. It's got as many features as some of these expensive options and isn't that much heavier.

We tested the Econ Burrow in the backcountry of Zion and Joshua Tree National Parks, and it kept us warm on nights near freezing while packing down surprisingly well too. It isn't the lightest or the warmest option out there, but the price is unbeatable for a quilt as functional as this one. The size, temperature, fill, and footbox style can all be customized as well, which will affect the price, but it should stay under the cost of nearly every other competitive option. For bargain shoppers, this is your bag.

Read review: Hammock Gear Econ Burrow 20

Best for Insane Packability


Sea to Summit Spark SpI 40


Sea to Summit Spark SpI 40
Top Pick Award

$320 List
List Price
See It

61
OVERALL
SCORE
  • Warmth - 30% 5
  • Weight - 25% 8
  • Comfort - 20% 6
  • Versatility - 15% 5
  • Features - 10% 6
Weight: 12.4 oz | Fill: 850+ Fill-Power Down
Extremely light for a mummy bag
Packs down to the size of a large grapefruit
Excellent zipper
Only appropriate for summer temperatures
Somewhat tight cut

There are those who go light, and there are those who go truly ultralight. The Sea to Summit Spark 40 is for those in the latter category. At a mere 12.4 ounces, this thing is so light and small, you might lose it in your pack. The Spark comes with a compression sack that shrinks it down to roughly one liter of space. We took this backpacking on a late summer overnight trip in southern Utah and easily fit everything into a 20-liter daypack. If you were really careful about it, you could probably get away with carrying this inside an ultra-running vest.

The folks over at Sea to Summit made this tiny package possible by stripping nearly everything off this hooded mummy bag. There's no draft collar or tube, only a half zipper. The baffles are also sewn through the shell fabric which harms thermal efficiency. It's not the warmest bag, but it is warmer than at least two of the quilts we tested. For seriously light summer missions, it's one cool piece of gear.

Read Review Sea to Summit Spark SpI 40


Why You Should Trust Us


We assembled an all-star crew to put these ultralight sleeping bags to the test, including Andy Wellman, Ethan Newman, Justin Simoni, and Jack Cramer. Andy has published guidebooks, hiked long distances in the Rockies, the Andes, and the Himalayas, and is no stranger to a night under the stars. Ethan has worked professionally outdoors for over a decade, including working as a rock climbing guide, wildland firefighter, wilderness ranger, and environmental educator. Justin has explored the more exhilarating peaks and ridgelines of Colorado, finishing bold fastpack routes on his unsupported multi-day adventures, and has assisted with guided ultralight backpacking trips in Kings Canyon NP, Rocky Mountain NP, and Gates of the Arctic NP. Finally, Jack is an accomplished climber and member of the Yosemite Search and Rescue team who has personally tested more than 60 different sleeping bags. Combined, they spend over 150 nights a year in a sleeping bag, from shiver bivvies on the sides of mountains to comfy nights around a campfire with friends, and we know how to get a good night's sleep outside.

Click to enlarge
Click to enlarge
Click to enlarge

To us, there's really only one way to test how a product truly performs—by using it. With this in mind, we tested these bags by sleeping in them a lot. We used them on windy desert nights and blizzards at 15,000 feet, along with everything in between. These bags have been all over the Rockies of Colorado and Wyoming, the deserts of southern Utah, and the high peaks and passes of the Khumbu, Makalu, and Manaslu regions of the Nepal Himalaya. Many people slept in each bag, and they spent both cozy and miserable nights in the wilderness, suffering through enough sweating and shivering to truly understand the meaning of "temperature ratings." One of our testers even caught two colds that he blames on sleepless nights spent in these bags in search of their hidden flaws. We went the extra mile to be sure we know what we're talking about, and we hope you find this review useful.

Related: How We Tested Ultralight Sleeping Bags

A solo campsite up in a side valley of the Khumbu, the famous part...
A solo campsite up in a side valley of the Khumbu, the famous part of the Himalaya that is home to Mt. Everest. The 20 Degree by ZPacks kept us nice and warm on what proved to be a chilly night.

Analysis and Test Results


To compare and score every quilt and bag as objectively as possible, we narrowed overall performance down to five metrics to evaluate each bag: Warmth, Weight, Comfort, Versatility, and Features. Because some of these categories are more significant than others, we weighted each metric according to the relative importance it has for an ideal UL sleeping bag. Keep in mind all these scores are comparative because we are only willing to speak for the products we test, not everything that exists in the entire ultralight sleeping bag market. This is why a 30-degree Fahrenheit sleeping bag might score highly in warmth; we are comparing it to other sleeping bags of similar weight, not a 0-degree winter behemoth.

Weight is a critical aspect of any outdoor gear, but it&#039;s...
Weight is a critical aspect of any outdoor gear, but it's particularly important to ultralight travelers.
Photo: Jack Cramer

While most of these bags use high-quality materials and well-executed designs, there limits to how lightweight things can get. In the realm of ultralight sleeping bag design, sometimes one aspect of performance must be sacrificed to aid another. For example, a tighter cut may be lighter and warmer, but far less comfortable. Keep this in mind as you read through this review to be sure you identify the best balance for your needs.

Related: Buying Advice for Ultralight Sleeping Bags

Comparing mummy bags on an extended road trip to the Bighorn...
Comparing mummy bags on an extended road trip to the Bighorn Mountains in northern Wyoming.

Ultralight vs. Traditional

What does it mean for a sleeping bag to be "ultralight"? Ultralight is a set of guiding principles to minimize weight, and thus maximize how far you can go and how much fun you have. However, this principle demands that every ounce counts. So if you're trying to balance warmth, weight, and comfort, you often only able to achieve two out of three. Some bags reduce weight by using a narrower cut or utilizing lighter, less durable materials. Still, others get by with generous interpretations of the definition of warmth.

A recent ultralight trend has been in favor of quilts rather than full sleeping bags. The idea is that any down or fabric underneath your body gets compressed and loses its loft, so why not eliminate it? Other bags eliminate hoods, shorten zippers, or strategically place the down fill to maximize warmth while keeping the weight minimal. Some of these bags are also designed to be part of a sleep system, relying on an insulated pad and the warm clothing you'll already be carrying. Still, other products blur the line between sleeping bags and quilts and cherry-pick great ideas from both types of offerings.

The bags and quilts in this review range from 9 ounces to a bit under two pounds. In contrast, our "backpacking" sleeping bag category runs from about 1.25 lbs to 3.5 lbs. There is some overlap and the differences may seem minor, but as ultralight hikers say, "ounces make pounds, and pounds make pain." If you're not sure which category is right for you, consider checking them both out before making a purchase decision.


Value


Although we don't factor value into our performance scores, we know it's a huge part of any purchasing decision. New gear is exciting, but most of us still want to pay the minimum amount for the gear we need. This means knowing whether shelling out extra money for a fancy sleeping bag is worth it. A common example is higher quality down that reduces weight, but raises the price. High fill power goose down offers the highest warmth-to-weight ratio of any commonly available insulation, but it is much more expensive than duck down, even at comparable fill powers. We can help you consider the pros and cons of each, but only you can decide if who much these differences are worth to you.

The Econ Burrow is a versatile, inexpensive quilt with quality...
The Econ Burrow is a versatile, inexpensive quilt with quality features.
Photo: Ethan Newman

One numerical way to assess value to compare to the overall score we've given product to its cost. For example, two bags might receive similar scores, but one could cost significantly less. All things being equal, the less expensive option would provide greater value. Without scoring for value, we've tried to highlight some less expensive options to help those looking to save a bit of cash. We believe that the Enlightened Equipment Revelation 20 provides top-notch performance with the fairest price tag. It's not inexpensive, but it does cost significantly less than top-of-the-line products that it directly competes with. The Hammock Gear Econ Burrow comes with a step down in performance, but we still think many people will be satisfied with its performance, especially considering the price savings. This model proves that you can still get a pretty good ultralight model on a tight budget.

The REI Trail Magma 30 quilt can be sealed up quite tight for colder...
The REI Trail Magma 30 quilt can be sealed up quite tight for colder nights using the included pad straps, neck draft tubes, neck cinch strap, and snap located at the top of the quilt. Especially for first-time quilt converts, this bag is a good choice.

Another ultralight option that seems to be a decent value is the Mountain Laurel Designs Vision Quilt. This hybrid quilt is extremely light at just 11.2 oz, however, it only offers modest levels of warmth. It's ideal for experienced ultralight folks who have their systems dialed and ready to use every trick in the book to stay warm. It's also one of the most affordable choices in the category, just be prepared for long wait times--these quilts are made to order.

This Patagonia bag is borderline acceptable in summer conditions...
This Patagonia bag is borderline acceptable in summer conditions, but absolutely miserable if the mercury drops.
Photo: Jack Cramer

Warmth


No matter how fast and light you go, eventually, you'll have to stop and rest. Getting a good night's sleep is essential to going hard again the next day. A warm sleeping bag is paramount to getting good sleep. Many ultralight hikers consider it the "ultimate layer." If your sleeping system, including your bag, pad, and warm clothes, can't keep you warm enough to recover after a long day, it doesn't matter how lightweight it is.

Fortunately, the bags we tested mostly offer good to excellent warmth-to-weight ratios, using quality materials and clever designs to maximize warmth. We strongly believe that you should choose your bag on the conditions and temperatures you expect to encounter. Because warmth is the main purpose of an ultralight sleeping bag, it counts for 30% of each product's overall score.


Sleeping bags work by trapping many tiny little pockets of air in the insulation, which prevents heat loss to the air around you. Currently, down feathers offer the best warmth-to-weight ratio of the common insulation types. The quality of down is rated according to its fill power, which is a measurement of the amount of loft a specific weight of down provides. Higher fill power numbers translate to more loft and better warmth-to-weight ratios. To keep the down feathers in place, manufacturers incorporate baffles into their sleeping bags. These are sewn pockets within the bag that ensure the insulation stays where it's supposed to, whether spread evenly or placed strategically. Box baffles, sewn-through baffles, and other designs all have their advantages and disadvantages but they share the same goal of keeping the down in place.

The other primary type of insulation is synthetic fibers. One advantage of synthetic insulation is that it's a more affordable material that's also easier to work with. Swaths of synthetic batting don't need an intricate system of baffles to stay in place, and if it gets wet it still retains a significant amount of insulative power. The drawback, however, is that synthetic fibers can't offer the same warmth-to-weight ratio as down. Synthetic insulation is also unable to pack down as small. For these reasons, down is a more popular choice in ultralight sleeping bags, but there are plenty of situations where a synthetic bag could be a better choice.

The Revelation 20 is the warmest one that we tested, and on a warm...
The Revelation 20 is the warmest one that we tested, and on a warm summer night, there was no need to fasten it up underneath us. Going light, Peter didn't even bother with a sleeping pad, and apparently slept all night with his headlamp on. Beware the power of the "sleep aids" legal in Colorado.

Temperature Ratings

Most sleeping bags and quilts come with a temperature rating recommended by their manufacturer (i.e. 20-degrees Fahrenheit). These numbers, however, rely on the honesty of the manufacturer, and marketing departments usually aren't known for their honesty. On one particularly rough night of "product testing," we slept in two bags, each rated to 15F at around 15,000ft. in Nepal. It happened to snow that night, and the temperature dropped to 10-15F. Wearing all of the clothes they had, two of our testers both spent the night shivering mercilessly and welcomed the 3:00 AM pre-dawn wake-up call simply to get moving again. These models did not perform well at their stated rating, so what gives?

There is a popular industry-standard test for sleeping bag warmth called EN 13537. For a sleeping bag to qualify for the test, however, it must have a hood. This excludes many of the bags and quilts in our review. If a bag can undergo EN 13537 testing it receives four ratings, but the two to look at are the "comfort" and "lower limit" ratings. Most manufacturers use the lower limit as their advertised rating, but be aware that the lower limit is defined as "the temperature at which a standard male can sleep in a curled position without waking." The "comfort" rating is the temperature a "standard female" can sleep in a comfortable and relaxed position.

In the case of the two of the bags we shivered inside in Nepal, the lower limit was listed as the temp rating. Although it's true that we didn't freeze to death that night, we were using the bags well below their comfort ratings in the upper 20's. Focus on these comfort ratings to get a better idea of a more reasonable temp limit. For sleeping bags that don't qualify for or don't receive an EN test, the manufacturers select their own rating to advertise. In the individual product reviews, we have tried to describe how these manufacturer ratings seem to compare to a standardized EN rating.

Letting the down uncompress before a night out in the Utah Hills. We...
Letting the down uncompress before a night out in the Utah Hills. We recommend unpacking your bag well before crawling into it so that it has time to regain its loft (and therefore maximize its warmth).
Photo: Ethan Newman

The quantity and quality of the insulation are big factors in the warmth of a bag, but we also found that the design can have a huge influence. Features like closed foot boxes, draft collars, hoods, zipper baffles, and pad attachment systems (for quilts) can differentiate products that utilize similar insulation. In general, hooded mummy bags seemed to be a bit warmer because they allowed us to burrow deep into the bag. Quilts, in contrast, inevitably allowed cold air to creep into the thermal envelope whenever we moved during the night, so we never seemed to feel quite as toasty.

Insulated Sleeping Pads and Quilts

All ultralight sleeping bags, but especially quilts, are designed to be used as part of a sleep system that includes the bag, a sleeping pad, and your clothing. Tailor your system to work in unison to keep yourself as comfortable and warm as possible. Most of the quilts we tested aren't designed to enclose the user fully but instead attach to an insulated sleeping pad to form a warm envelope. The theory behind quilts is that the sleeper compresses any sleeping bag insulation below them, negating the insulating effect it would otherwise have, so why not ditch this unnecessary material and save the weight? This can work well but requires careful selection of a sleeping pad to match your quilt, and the pad needs to offer great insulation from the ground.

Sleeping pad insulation power is rated on a scale called R-value. The higher the R-value of a sleeping pad, the more insulation it offers from the ground. During our testing on cold nights, we found that some quilts left chilly drafts, and we would have liked some extra insulation below us to fill in these gaps. Make sure your insulated pad fits your quilt, and that any extra clothing won't compress the insulation and reduce its effectiveness. Pads do come in different widths, and a wider pad may spread out a quilt too much, leaving less room for you to sleep underneath.

Related: Best Backpacking Sleeping Pad of 2021

We made a point of testing each of these bags while sleeping in temperatures very close to their stated ratings, catching two colds and spending more than a few nights shivering in the process. These experiences taught us which bags are warm and which are not, and we rated these bags on comparative warmth, meaning the warmest got the highest score, and the coldest got the lowest score.

Several bags tied for warmth (in proportion to their rating): the EE Revelation 20, the Zpacks 20 Degree, and the Western Mountaineering Summerlite. The Western Mountaineering bag is a hooded mummy bag that creates a nearly complete thermal envelope around the sleeper, sealing in as much warmth as possible. The Zpacks and Revelation bags were also very warm, but the lack of a hood requires a warm hat or hooded jacket to insulate your head.

We saw a wide range of loft among ultralight sleeping bags. Six...
We saw a wide range of loft among ultralight sleeping bags. Six ounces of synthetic Primaloft Gold insulation (left) found in the thin Patagonia sleeping bag hardly compares to 13 ounces of 950FP goose down (right).
Photo: Jack Cramer

While we love quilts for their versatility and spaciousness in warmer weather, our testing revealed that in cold weather, they don't seem to seal off as well and didn't keep us as warm as mummy-style bags.

The REI Magma Trail 30 quilt fared pretty well in our testing when it came to warmth for a quilt but was a bit finicky to set up correctly. Much of its warmth comes from removing features that would ordinarily add to the versatility of a quilt. For example, the Magma's toasty footbox is important for keeping your feet warm, but on a hot night, it lacks the option for any sort of foot ventilation, or the ability to transform the entire quilt into a blanket. This may make things a little too toasty in warm summer conditions.

The Summerlite fluffs up to a warm 4-inch fill and is one of the...
The Summerlite fluffs up to a warm 4-inch fill and is one of the toastiest bags we tested.
Photo: Ethan Newman

Weight


What separates this review from our other sleeping bag reviews is the emphasis on weight. Ultralight backpackers are often distinguished from regular backpackers by having a base weight of their overnight pack (non-consumable gear) of under ten pounds. The idea is that by willing to make some compromises in comfort or convenience ultralighters can enjoy the considerable benefits of a light pack. A ten-pound base weight can be achieved with any of the products in this review, but if you're going super ultralight, pay extra attention to the weight score. As the second most important metric, weight accounted for 25% of a product's final score.

It is worth noting that in almost all cases, we chose the option or version of each model that was the lightest weight, usually going with a higher temperature rating to do so. For those who want a bit more warmth and are willing to carry a few extra ounces to have it, there are usually slightly heavier and warmer options available. Many of the products we tested have an incredible spread of parameters you can customize, including overfilling the bag or adding draft tubes. These options can significantly affect the warmth of the bag but may delay your order and add to the price of the product.


When it comes to ultralight sleeping bags, most managed to shave weight with a combination of high-quality insulation and pared-down features and design. Down provides one of the best warmth-to-weight ratios, which is why it is the insulation of choice in the very lightest products. Down is rated by its fill power, and the higher the number, the more loft it has, and thus the higher quality. In most cases, the bags tested in this review use down with a fill power of 800 or more. The fill power and quantity of down used in each competitor can be found in the specs listed for each product.

Not all UL sleeping bags pack down equally!
Not all UL sleeping bags pack down equally!
Photo: Ethan Newman

In the case of most quilts, weight is saved by eschewing fabric or insulation on the underside of the bag. Lightweight straps or string systems help latch the sides of the quilt around the user or a sleeping pad, thereby eliminating the weight of a zipper as well. Quilts also forego a hood, thus avoiding the weight of more fabric and insulation. Some models also feature snaps to wrap the quilt around one's neck while sleeping — a nice feature but it can increase weight.

Mummy bags, on the other hand, employ other tricks to save weight. Ultralight fabrics, both on the shell and baffles, reduce weight but usually make the bags more delicate. Smaller zippers have the same effect, and there is often also shortened to trim ounces but reducing venting possibilities. Most ultralight mummy bags have rather narrow dimensions because less fabric is needed so the bag can be further lightened.

When calculating the overall weight of your sleep system, factor in how versatile your sleeping bag and quilt might be for different tasks. Quilts and full zip sleeping bags can keep you warm on cold mornings as you get ready for the day's hike, which may mean you are able to optimize your clothing layers better. If you think you'll require additional warmth for your head at night, as most quilt users will probably want, find a nighttime insulated cap that can also play double-duty while out on the trail.

The Vesper 32 is impressively light and packable at 15 ounces, but...
The Vesper 32 is impressively light and packable at 15 ounces, but the compression sack made concerning ripping noises when we tightened it down. Not an issue if you simply stuff this bag into the bottom of your pack sans sack.
Photo: Ethan Newman

We weighed these bags individually on an independent scale to determine the weight and then assigned the scores comparatively. In the case of quilts where extra straps or buckles were required to close up the quilt or affix it to a sleeping pad, we also included that weight. However, we chose to weigh any included stuff or compression sacks separately.

One stand out in this metric is the Sea to Summit Spark 40 mummy bag. It comes in at an insane 12 ounces and packs down to the size of a water bottle. To achieve this impressive weight it eschews baffles for a sewn-through design to keep the insulation in place. This construction, however, is less thermally efficient because it creates uninsulated zones at the seams.

The Mountain Laurel Designs Vision Quilt and Patagonia Lightweight Sleeping Bag are both synthetic models that are even lighter on the scale. At 10 oz, the Patagonia is the lightest bag in the review, but we don't believe it provides enough warmth to be a tempting choice to most shoppers. The Vision Quilt, in contrast, weighs just an ounce more (11 oz total) and offers a more respectable level of warmth. It's a good choice for any seeking an affordable featherlight choice, or when wet conditions make down insulation less desirable.

If you&#039;re concerned about packed size, consider a third-party...
If you're concerned about packed size, consider a third-party compression sack. The included stuff sack with the Mountain Laurel Designs Vision Quilt (right) left the bag twice as large as a third-party sack (left).
Photo: Jack Cramer

Comfort


The other half of the equation for a good night's sleep is comfort. Things like drafts, drawcords dangling in your face, buckles wedged underneath you, or a claustrophobic shape can all prevent you from sleeping soundly. And if you sleep well, you should be able to perform better the next day. There's nothing worse than to loathe getting into a subpar sleeping bag or quilt, which is why we think comfort is important enough to make it 20% of the overall score.


When assessing for comfort, the first thing we looked at is how well the bag fits. Our head testers are 5'11" and 5'8" and fairly trim, so we ordered all of the test models to suit a person 6'0" tall and standard width. By ordering them all the same size, we were able to compare the fit of each bag to the same standard. Luckily for you, most of the bags in this review come in different height and width options which makes it easy to customize a bag for your particular shape.

Two aspects of a sleeping bag or quilt's fit were immediately noticeable: the length and the width. Despite many being marketed for a 6'0" person, some bags were too short, leaving it uncomfortable to cinch the collar over the shoulders or wear the hood over our heads.

Comparing and testing mummy bags in the Bighorn Mountains of...
Comparing and testing mummy bags in the Bighorn Mountains of Wyoming, we found that the Vireo had by far the most spacious fit through the torso, and was also really light!

Rather than reduce the length, most ultralight quilts instead reduce the width to minimize weight. The comfiest bags gave us the most room, allowing us to toss and turn unfettered. Mummy bags are historically claustrophobically cut. But some, like the Feathered Friends Vireo UL, were generously fit. Quilts, on the other hand, offer plenty of room, but sometimes yielded claustrophobic feelings when we utilized their pad attachment systems. Some quilts also were too narrow to wrap ourselves in on chillier nights, no matter how much we repositioned.

We were satisfied with the modest warmth of the Vision Quilt in warm...
We were satisfied with the modest warmth of the Vision Quilt in warm summer conditions when paired with appropriate layers of clothing, the right sleeping pad r-value, and careful campsite selection. We were rather upset when snow started to fall unexpectedly.
Photo: Jack Cramer

In addition to the fit of a bag or quilt are the little details that can detract or enhance comfort. For example, the position of drawstrings, the feel of a fabric, or the shape of the hood can make or break a good night's sleep. All these small elements also influenced the comfort score of each product.

Ultimately, the Feathered Friends Vireo UL scored as the most comfortable sleeping bag or quilt. Its vast and spacious cut in the torso is designed to accommodate the extra fill of an insulated jacket, but it also left us feeling free to move about as desired. Many other bags/quilts scored just a little lower, including the Sierra Designs Cloud 35, which was unique out of all the sleeping bags we've tested in that it does away with a zippered design completely. Instead, it uses an extra-wide comforter for you to wrap your body around.

The Sierra Designs Cloud 800 35 unique zipperless design makes it...
The Sierra Designs Cloud 800 35 unique zipperless design makes it easy to get into and out of the sleeping bag

None of the top models of sleeping bags/quilts that we composed reviews for scored outstanding when it comes to comfort. This doesn't in any way mean they're uncomfortable but it does highlight that compromises in comfort are made to keep sleeping bags ultralight. If the compromises we've documented across all these products in the name of wearing the coveted "ultralight" label is too much, consider a more traditional backpacking sleeping bag.

Related: Best Backpacking Sleeping Bag of 2021

For warmer nights, the REI Trail Magma 30 quilt can be loosely...
For warmer nights, the REI Trail Magma 30 quilt can be loosely fitted to the pad using the included pad straps, and left open at the top of the quilt.

Versatility


If you want a three-season sleeping bag, or are planning an epic six-month thru-hike that will span the seasons from cool spring into hot summer and back into a cool fall, then versatility is a critical metric. Versatility is the ability of the bag to be used comfortably in a variety of situations. Questions we asked ourselves when rating each bag for versatility were: is it possible to wrap oneself up like a cocoon to stay warm on the coldest nights? Likewise, is it feasible to open the bag up and ventilate to stay cool on the warmest of nights? Sleeping bags that could do both with ease were the highest scorers when it came to versatility, and sleeping bags that pigeonholed themselves into only being practical in one season or temperature range scored the lowest.


In general, quilts are more versatile than ultralight mummy bags, whose half-length zipper designed with weight savings in mind often made it even harder to ventilate on warm nights. Quilts and bags that included full-length zippers, or quilts that were long enough and broad enough to wrap oneself up fully, fared the best because they most easily allowed for staying warm on cold nights. Besides just being able to be used in both hot and cold seasons, we also looked at whether a bag would be serviceable in wet climates. Ultralight bags that used synthetic insulation, which will not clump and will continue to provide substantial insulation even when wet, received a bonus.

Our testers enjoying themselves while comparing/contrasting the...
Our testers enjoying themselves while comparing/contrasting the versatility of the products. Being able to poke your feet out of the bottom of a sleeping bag allows you to walk about your campsite while staying wrapped up on cold mornings.

We also looked at whether a bag used a DWR (durable water repellent) treatment on its outer shell to protect it from absorbing liquids such as condensation, or used a naturally water-resistant fabric such as Pertex Quantum to accomplish the same thing. Lastly, we looked at how packable a sleeping bag was. The smaller it packs down, the easier it is to carry along with you, and for a few outdoor sports like bike touring or bike packing, this is a critical component of whether a piece of gear can be useful or not. As an important metric, but not the most crucial metric, we weighted versatility as 15% of a product's final score.

On a chilly morning in the desert, we enjoyed the versatility of...
On a chilly morning in the desert, we enjoyed the versatility of being able to wear the Flicker 40 with our feet out and the zipper done up, at least until the sun hit.

The most versatile product without a doubt is the Feathered Friends Flicker 40 UL. This bag can transition seamlessly between use as a quilt or a fully enclosed hoodless mummy bag, offering protection for a variety of situations. On the warmest nights, it can be used as a spread-out blanket, which is also ideal for two people, or as a quilt with an enclosed foot box by tightening the drawstring on the end and zipping it up partway. The full-length zipper means that on cold nights, it is possible to seal it up entirely and trap the warm air in with the help of a neck baffle with dual drawcords. No other bag so easily met the demands of all seasons. Although we tested the 40F version of this bag, it also comes in 30F and 20F versions for those who live and play in colder climates or seasons.

The Flicker 40 is one the quilts in the review that is capable of...
The Flicker 40 is one the quilts in the review that is capable of opening up fully into a blanket on warmer nights. It's wide enough for two people to fit under.

Also near the top in the versatility department is the Zpacks Classic. A hoodless mummy bag that is rated to 20F features box baffle construction, and a DWR coated Pertex Nylon shell, the Zpacks Classic is ideal for cold nights. It also has a ¾ length zipper that allows one to open it up like a quilt for warmer nights. If you want an ultralight bag that you can utilize in all three seasons, be sure to pay attention to our versatility ratings.

One of the nice things about quilts is how easily they function as...
One of the nice things about quilts is how easily they function as blankets to keep one warm while hanging out around camp.

Features


The features metric is the last piece of the puzzle to understand how well an individual ultralight sleeping bag works. A sleeping bag is simply a down-filled sack or blanket designed to keep you warm at night, and the features are all those little components that make it work. Drawstrings, draft collars, zippers, hoods are all designed to enhance a sleeping bag functionality and make it a more useful addition to an efficient sleep system that conserves all the necessary BTUs you produce to sleep soundly.


The most common features found on these bags are zippers, draft collars, cinch cords around the neck, face, hood, or feet, and in the case of quilts, pad attachment systems. When assessing for features, we looked first at whether a bag's specific features functioned well or whether they were finicky and annoying. Then we compared them to similar features on the other bags and rated them in comparison to all the others.

The unique designs of the Sierra Designs Cloud 800 do take a fair...
The unique designs of the Sierra Designs Cloud 800 do take a fair bit more material and stitching when compared to other bags we've tested.

Zippers that wouldn't stay zipped or were continually getting stuck in fabric, pad straps that wouldn't stay attached or wouldn't lock in place, and drawcords that didn't have buckles or wouldn't stay tight, are examples of poor-performing features that caused us to knock the score down a bit.

Once again, the Flicker 40 receives the highest score for features. Not only did it have a ton of features — full-length zipper with a reinforced draft tube, drawcord enclosure at the feet, dual drawcord and neck baffle at the head, optional attachment points for DIY pad straps — but they all worked well. The difference in having a full zipper versus just intermittent buttons or straps to enclose the quilt turned out to be a game-changer for trapping in heat.

Click to enlarge
Click to enlarge

The Sierra Designs Cloud 35 also had a great set of unique features. In fact, this sleeping bag seemed to really want to shine in a category all of its own between a sleeping bag and quilt. Zippers getting stuck within the shell fabric of the bag itself will never be a problem because there are no zippers to get stuck! Along with a full zipperless design, the Cloud 35 has an interesting footbox vent, and an oversized quilt useful for either keeping loose on warm nights or tight on colder ones. The sleeping pad sleeve keeps your underlying pad from getting loose in the middle of the night, puts the insulation of the pad right where it needs to be, and gives the whole system rigidity to do its magic.

The Revelation 20 also has a great set of features, including a cleverly designed and versatile footbox that both vents and allows the entire quilt to transform into a blanket. Its warmth to weight ratio, especially when compared to its price for a US-made quilt, is also quite remarkable, and makes it worth your time to consider.

A warm night in the Black Canyon was a great excuse for Cowboy...
A warm night in the Black Canyon was a great excuse for Cowboy camping in the Katabatic Gear Palisade 30. We loved the adjustability of the pad attachment straps on this pleasant evening.

Conclusion


The world of sleeping bags is flush with options, everything from old-school, square-cut monstrosities to airy space-age quilts and everything in between. For this review, we specifically singled out ultralight sleeping bag and quilt options because more people seem to be noticing that backpacking is more fun when your pack is light. Ultralight sleeping bags are best suited for warmer temperatures, but with proper planning and well-designed systems, they can be pushed into the shoulder seasons. These are for people going fast and light, where any extra ounces will slow you down and keep you from your goals. Activities like thru-hiking, fastpacking, bikepacking, alpine climbing, adventure racing, and bike touring all employ ultralight systems to go further and faster in the wilderness. We poured over scores of ultralight sleeping bags and quilts to find the best models and put them to the test from mountains to deserts to forests to give you the best recommendations possible.

Andy Wellman, Ethan Newman, Justin Simoni, and Jack Cramer