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The 5 Best Ultralight Sleeping Bags of 2024

We get moving fast and light with ultralight sleeping bags from Feathered Friends, ZPacks, Western Mountaineering, and more to find the best option for you
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Best Ultralight Sleeping Bag Review (Testing sleeping bags side-by-side.)
Testing sleeping bags side-by-side.
Credit: Justin Simoni
By Justin Simoni, Andy Wellman, Ethan Newman, and Jack Cramer  ⋅  Feb 28, 2024

The Best Ultralight Sleeping Bags for 2024


Over the last ten years, we have bought and tested over 45 ultralight sleeping bags. This review compares 17 of the best models. Our expert gear team of rock climbers, thru-hikers, and fast packers spent countless nights sleeping in these bags across the globe. From frigid mountain summits to low desert canyons, these bags have been carried for miles and miles in different environments. We also put them through controlled temperature testing. Whether this is your first foray into the ultralight world or you are an old hat looking to update your gear, we're here to help you find the perfect bag for your ultralight adventures.

If you're an ultralight enthusiast, we've got your back (literally — we can save you from carrying extra weight!) Check out our sleeping pad review to find the most comfortable lightweight model and our picks for the best ultralight tents and top-ranked backpacking tents for a lightweight shelter to carry on the trail. We've also tested a ton of other backpacking gear and put together a backpacking checklist to get you out the door and on your way.

Editor's Note: This ultralight sleeping bag review was updated on February 28, 2024, to include new and updated models.

Top 17 Ultralight Sleeping Bags - Test Results

Displaying 1 - 5 of 17
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Awards Editors' Choice Award  Top Pick Award   
Price $549.95 at REI
Compare at 2 sellers
$409 List$449 List
$429.00 at Feathered Friends
$365 List$500 List
$500.00 at Backcountry
Overall Score Sort Icon
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Pros Excellent warmth and weight, well thought out features, horizontal box baffles, generously-sized footboxWarm for an ultralight bag, simple and versatile design, box baffle construction, waterproof stuff sackExceptional warmth to weight, best for FKTs and lightning quick mountain adventures, simpleClosed footbox to blanket versatility, excellent materials and sewing, unique pad strap attachment systemLightweight, warm, seals well for a quilt
Cons Expensive, not as versatile as a quiltA little constricting, small foot box, not the best neck draw cord designLess versatile than other bags, cannot unzip at all to wear as a blanket or dry out, harder to climb in/get outSlim fit may not work for everyone, slight animal smell when newHard to vent, pad attachment system not intuitive
Bottom Line A seriously toasty bag to bring on any adventure that won't feel like a boat anchor in your packA top-scoring bag that's warm and versatile enough for full three-season use, while weighing impressively littleTailor-made for light and fast ultralight backpackers, fastpackers, mountaineers, and FKT enthusiasts that demand both warmth and a light weightThis versatile quilt has a cinch-able and zippered footbox aimed at the serious thru hikerA very lightweight and warm quilt designed for three season use
Rating Categories Therm-a-Rest Hyperi... ZPacks Classic Feathered Friends V... Katabatic Gear Flex... Western Mountaineer...
Warmth (30%)
9.0
8.5
6.8
8.7
6.7
Weight (25%)
6.5
6.9
8.5
5.6
8.0
Comfort (20%)
8.0
6.0
8.0
6.0
7.0
Versatility (15%)
6.0
9.0
6.0
8.0
6.0
Features (10%)
8.0
5.0
5.0
8.0
7.0
Specs Therm-a-Rest Hyperi... ZPacks Classic Feathered Friends V... Katabatic Gear Flex... Western Mountaineer...
Manufacturer Stated Temperature Rating 20°F 20°F 25°F lower half, 45°F upper half 22°F 26°F
Measured Weight (bag only) 21.4 oz 20.3 oz 16.2 oz 23.6 oz 17.5 oz
Stuff Sack Weight 1.6 oz 0.9 oz 0.8 oz 0.6 oz 0.9 oz
Stuffed Size 6" x 8" 6" x 12" 7" x 10" 7" x 12" 6" x 10"
Manufacturer Claimed Weight 20.0 oz 19.8 oz 16.7 oz 23.9 oz 17.5 oz
Fill Weight 12.5 oz 13.1 oz 9.4 oz 15.4 oz 10.5 oz
Shell Material 10D Nylon RipStop w/DWR Ventum ripstop nylon w/DWR Pertex Endurance UL Pertex Quantum Eco ripstop (.85 oz/yd) 7D shell
Fill Power 900 fill RDS Nikwax hydrophobic goose down RDS 900 fill RDS DownTek PCF-FREE water-resistant goose down 950+ fill goose down 850 Exped duck down 850+ fill down
Style Hooded mummy Hoodless mummy Hoodless, zipperless mummy Quilt, unzip footbox for blanket Quilt
Construction Horizontal box baffle consruction Vertical upper baffles and horizontal lower baffles, box baffle construction No hood, no zipper and a variable fill Continuous Horizontal Baffles No hood, no zipper
Shoulder Girth 57" 61" 64" 54" 59"
Hip Girth 49.5" 61" 48" 46" 51"
Foot Girth 43" 35" 38" 40" 38"
Zipper Length 1/2-length side zip at top 3/4-length No zipper 1/4-length at footbox No zipper
Sizes Small, regular, long Slim, standard, and broad (girth) short, medium, long, x-long and xx-long (length) 62", 68", and 74" Small, regular, long, small wide, regular wide, long wide Regular, long
Temp Options (degrees Fahrenheit) 20, 32°F 10, 20, 30, 40°F 25, 45°F 15, 22, 30, 40°F 26°F


Best Ultralight Hooded Mummy Bag


Therm-a-Rest Hyperion 20


76
OVERALL
SCORE
  • Warmth 9.0
  • Weight 6.5
  • Comfort 8.0
  • Versatility 6.0
  • Features 8.0
Weight: 21.4 oz. | Fill: 900 Fill-Power GooseDown
REASONS TO BUY
Great warmth-to-weight ratio
High-quality goose down
Built-in pad straps
REASONS TO AVOID
Not for the budget-minded
Heavier than some options
Not as versatile as a quilt

With our lab and field testing finished and metrics tabulated, one bag was head and shoulders above all the others. The Therm-a-Rest Hyperion 20 takes the crown and earns our Editor's Choice for Best Ultralight Hooded Mummy Bag. With such a stacked lineup of frankly incredible bags and quilts, what are the defining traits that pushed the Hyperion to legendary gearhead status? The warmth and comfort felt when sleeping in this bag rivaled all its peers, and we must thank the expert designers who crafted such a product. We also found all the features found on the Hyperion to work excellently. We especially loved the two-sided half-length zipper and snap by the hood that lets you keep your face covered while allowing your body a little ventilation. The addition of simple and effective pad straps kept our pad from moving away in the middle of the night, and now we can't think of living without them.

We'd suggest the Hyperion to everyone if we could, but there are a few details we can't overlook. The first is the price. This sort of excellent quality in a sleeping bag doesn't come cheap, nor do the high-end materials that are used: RDS 900-fill goose down with a hydrophobic treatment and 10D shell material are best-in-class. The other “gotcha” is that just being a sleeping bag means that the Hyperion isn't as versatile as a quilt like the Katabatic Gear Flex 22. Quilts aren't for everyone either, but there's something to be said about being able to easily and so broadly adjust how much heat is retained by your sleep system with little effort. A sleeping bag like the Hyperion just can't pull off those tricks.

Read more: Therm-a-Rest Hyperion 20 review

Getting cozy in the Therm-a-Rest Hyperion. The 3/4 zip makes it easy to get in and out of the mummy bag.
Credit: Justin Simoni

Most Versatile Quilt


Feathered Friends Flicker 40 UL


69
OVERALL
SCORE
  • Warmth 4.0
  • Weight 7.4
  • Comfort 7.0
  • Versatility 10.0
  • Features 9.0
Weight: 19.1 oz | Fill: 950+FP Goose Down
REASONS TO BUY
Super high fill power down
Functions as a quilt or a mummy bag
Full-length zipper with baffle gives you complete enclosure
REASONS TO AVOID
No hood
Expensive
Not the lightest bag available

We love the versatility of the Feathered Friends Flicker 40 UL, and it's a big part of why this bag lives near the top of our charts. Whether trying to ventilate on a hot night or bundle up when the mercury drops, this bag has you covered. A full-length center zip enables you to use it as either a hoodless mummy bag or a flat quilt, giving you two great sleeping options. 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 best and lightest materials in this masterpiece.

We opted to test the 40°F version to try out the lightest Flicker available, and while it did keep us warm in that temperature range if it dips into the 30s, you will not be so toasty. If you need added warmth for colder nights, Feathered Friends offers this bag in 30°F and 20°F options, but those bags are heavier. The Flicker's 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 Zpacks Classic is another highly versatile option. Though it is a mummy bag, the ¾ length zipper allows it to open up almost all the way and be used as a quilt on warmer nights.

Read more: Feathered Friends Flicker 40 UL review

The Flicker 40 is more than just a quilt, with its full-length zip that transforms the bag into a mummy-style.
Credit: Justin Simoni

Quilts vs. Mummy Bags
We know that quilts versus mummy bags can be a polarizing topic. There are excellent arguments on both sides of this issue; therefore, we chose a favorite bag for each type. Some of our testers prefer quilts, and 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.

Best Synthetic


Enlightened Equipment Revelation APEX 30


63
OVERALL
SCORE
  • Warmth 5.5
  • Weight 5.3
  • Comfort 7.0
  • Versatility 8.0
  • Features 7.0
Weight: 24.6 oz | Fill: 4oz/yd² APEX synthetic insulation
REASONS TO BUY
Insulates well, even when wet
Generous cut
Excellent value
REASONS TO AVOID
Takes up lots of volume
Heavier than most quilts

It took us a while to warm up to the idea of testing a synthetic bag in the ultralight category, but we're happy to report that the Enlightened Equipment Revelation APEX 30 left us toasty. We've since given it the pioneer, Top Pick for Best Synthetic. In lieu of down, the APEX 30 uses its namesake synthetic insulation and a lack of baffles to give a 30°F limit rating. This works great, and the quilt comes with a ton of great features to keep you as warm as you need to be and quite comfortable.

You do pay a bit for going synthetic. Down fill just has a much superior warmth-to-weight ratio and packs down much smaller than this quilt can even dream of doing. But if you have space in your pack and don't mind a few more ounces to carry, give this quilt a closer look. The quilt might not be as light, but the price beats almost every down bag in this review. With a comparable price, the Therm-a-Rest Vesper 32 offers the warmth and water resistance of down.

Read more: Enlightened Equipment Revelation APEX 30 review

The footbed of the Revelation APEX 30 can either be cinched closed or left open for a more blanket-like feel.
Credit: Justin Simoni

Best for a Tight Budget


Hammock Gear Economy Burrow 20


66
OVERALL
SCORE
  • Warmth 6.7
  • Weight 4.8
  • Comfort 7.0
  • Versatility 8.0
  • Features 8.0
Weight: 25.8 ounces | Fill: 850 Fill-Power Duck Down
REASONS TO BUY
Bargain for what you get
Great versatility
Customizable
REASONS TO AVOID
Heavier than others at limit rating
Bulkier than other quilts

Some ultralight backpackers will find it worthwhile to fork over some extra cash to save weight. However, the Economy line from Hammock Gear proves that you don't need to break the bank for a quality lightweight quilt. We tested the Hammock Gear Economy Burrow 20, and we were surprised at how well it performed despite the price being less than half that of some of the premium models. It's got as many features as some of the more expensive options and isn't that much heavier.

We took the Economy Burrow to the backcountry of Zion and Joshua Tree National Parks, as well as deep in Colorado's backcountry. It kept us warm on nights near freezing with the added benefit of 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 foot box style can all be customized, which will impact the price, but it should stay under the cost of nearly every other competitive option. For bargain shoppers, this is your bag. If weight is your key priority, the Western Mountaineering HighLite is worth checking out. This bag packs in eight ounces of 850+ down for a total weight of 15 ounces.

Read more: Hammock Gear Economy Burrow 20 review

The Economy Burrow won't slide off you in the middle of the night thanks to its stretchy pad straps.
Credit: Justin Simoni

Best for Moving Fast and Light


Feathered Friends Vireo UL


72
OVERALL
SCORE
  • Warmth 6.8
  • Weight 8.5
  • Comfort 8.0
  • Versatility 6.0
  • Features 5.0
Weight: 16.2 oz | Fill: 950+ Goose Down
REASONS TO BUY
Exceptional warmth-to-weight ratio
Generous shoulder girth
Keeps things simple
REASONS TO AVOID
Less versatile than other bags
No zipper to easily ventilate

Do you have a gear room plastered with posters of Karel Sabbe and Heather Anderson— and that's where the kitchen's digital food scale is hiding? You may have a serious case of FKT-itis. Let the Feathered Friends Vireo UL be the cure. At only a touch over a pound, this hoodless, zipperless sleeping bag invests 9.8 ounces of the finest 950+ goose down in keeping you warm between cat naps on the trail towards Mount Katahdin or perched precariously on the crest of the Sangre de Cristos en route to Salida. The shell material is a whisper-light 10D, with a 15D lining. The only accouterment allowed is a single cinch strap by the head. Break out your insulated jacket while getting your shuteye, as one way this bag cuts seriously weight is by having less down on the top half of the bag as it does the bottom. This means packability is excellent for the prime real estate found in your 30-liter fastpack.

This somewhat extreme design does mean a lot of compromises, and this bag isn't going to be attractive to everyone. The bottom of the bag is limit-rated to 25°F, and there's no zipper or any other vents to get some air down there. The upper is limit rated to 45°F so you best be bringing along your favorite puffy. The price is a premium one for so few features. If you're not already cutting your proverbial toothbrush in half and cold-soaking your oats for the morning's no-cook meal, you may be better off with a different choice. Still, we find the Vireo oh so comfy without any zippers or other features next to our skin and the perfect companion when you feel the need: the need for speed. Like the idea of zippers but don't care for snagged fabric? The Feathered Friends Hummingbird UL 30 gets around this with a special zipper that has an internal piece of flexible plastic. Plus, this two-way zipper system allows you to vent your feet or dump heat on warmer nights.

Read more: Feathered Friends Vireo UL review

The design of the Vireo lacks zippers and buckles to keep it as simple as possible.
Credit: Justin Simoni

Compare Products

select up to 5 products to compare
Score Product Price
76
Therm-a-Rest Hyperion 20
Best Ultralight Hooded Mummy Bag
$550
Editors' Choice Award
73
ZPacks Classic
$409
72
Feathered Friends Vireo UL
Best for Moving Fast and Light
$449
Top Pick Award
72
Katabatic Gear Flex 22 Quilt
$365
70
Western Mountaineering AstraLite
$500
69
Feathered Friends Flicker 40 UL
Most Versatile Quilt
$469
Top Pick Award
69
Therm-a-Rest Vesper 32
$400
68
Western Mountaineering SummerLite
$505
67
Sea to Summit Spark Ultralight 28
$409
67
Feathered Friends Hummingbird 30 UL
$549
66
Hammock Gear Economy Burrow 20
Best for a Tight Budget
$270
Best Buy Award
66
Outdoor Vitals StormLoft Down TopQuilt
$330
65
Enlightened Equipment Revelation 20
$335
63
Enlightened Equipment Revelation APEX 30
Best Synthetic
$200
Top Pick Award
61
Katabatic Gear Palisade 30
$340
60
Western Mountaineering HighLite
$435
53
Big Agnes Fussell UL Quilt
$280

ultralight sleeping bag - 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.

Why Trust GearLab


We pored 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. The only way to test a product's performance is by using it. With this in mind, we tested these bags by sleeping in them — a lot. We used them on windy desert nights, blizzards at 15,000 feet, and 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 Himalayas. Many people took turns sleeping in each bag, spending 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 searching for 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.

Our ultralight sleeping bag testing is divided into five rating metrics:
  • Warmth (30% of total score weighting)
  • Weight (25% weighting)
  • Comfort (20% weighting)
  • Versatility (15% weighting)
  • Features (10% weighting)

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 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 Yosemite Search and Rescue team member 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.

A magnificent campsite, and a great place to test out the best...
A magnificent campsite, and a great place to test out the best ultralight sleeping bags and quilts. This is near the small village of Samdo on the Manaslu Circuit in Nepal, using the Palisade 30 and The North Face Superlight 15.
The Sea to Summit Spark is great for desert backpacking when the...
The Sea to Summit Spark is great for desert backpacking when the nights don't get too cold.
With the hood tightened up as it is here, this bag felt a bit too...
With the hood tightened up as it is here, this bag felt a bit too short for our head tester, who didn't find it comfortable to use with the hood pulled over his head.

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 its relative importance 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.

While most of these bags use high-quality materials and well-executed designs, there are 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.

Gettin' cozy! Our team at GearLab hand-tested each of these bags under the stars to see which were the best.
Credit: Justin Simoni

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 are 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 nine 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. Still, 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 how much these differences are worth to you.

ultralight sleeping bag - the economy burrow 20 is a versatile, inexpensive quilt with quality...
The Economy Burrow 20 is a versatile, inexpensive quilt with quality features.
Credit: Ethan Newman

One numerical way to assess value is to compare the overall score we've given a 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 highlighted some less expensive options to help those looking to save a bit of cash. The Katabatic Gear Flex 22 Quilt provides top-notch performance with a very fair 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 Economy Burrow 20 comes with a step down in performance, but many people will be satisfied, especially considering the price savings. This model proves that you can still get a good ultralight sleeping bag on a tight budget. The Outdoor Vitals StormLoft Down TopQuilt is a good value for someone's first foray into quilts, given its stated limit temperature rating and the 800+ fill power down it comes with. One of the least inexpensive quilts, the Enlightened Equipment Revelation APEX 30 uses synthetic fill which is much cheaper than down. It'll be heavier and bulkier, but you can't ignore the price tag.

ultralight sleeping bag - the outdoor vitals stormloft has a combination of horizontal and...
The Outdoor Vitals StormLoft has a combination of horizontal and vertical baffles to keep its down in place.
Credit: Justin Simoni

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. You should choose your bag based 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, 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. Baffles are employed as a method of keeping the down feathers in place. 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.

ultralight sleeping bag - the horizontal baffles of the hyperion help keep the insulation in...
The horizontal baffles of the Hyperion help keep the insulation in place to provide a more evenly dispersed loft.
Credit: Justin Simoni

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.

ultralight sleeping bag - the revelation 20 is one of the warmest one that we tested, and on a...
The Revelation 20 is one of the warmest one that we tested, and on a mild 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°F). 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 15°F at around 15,000 ft in Nepal. It happened to snow that night, and the temperature dropped to 10-15°F. 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 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 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 20s. 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 described how these manufacturer ratings compare to a standardized EN rating.

ultralight sleeping bag - 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).
Credit: 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 footboxes, draft collars, hoods, zipper baffles, and pad attachment systems (for quilts) can differentiate products that utilize similar insulation. In general, hooded mummy bags were 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 tested quilts 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 weight? This can work well but requires a 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 Pads of 2024

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 were warm and which were not, and we rated these bags on comparative warmth, meaning the warmest got the highest score and the coldest got the lowest score.

The Therm-a-Rest Hyperion 20 came out in our testing to be the warmest sleeping bag in our entire lineup. It uses 12.5 ounces of 900 fill goose down to keep you toasty, as well as features that don't allow too much heat to escape. We really enjoyed how tightly the hood can cinch around our face and the two-way zipper that allows us to keep the hood on while ventilating our body.

ultralight sleeping bag - for extra warmth, the hood of the hyperion 20 can be cinched around...
For extra warmth, the hood of the Hyperion 20 can be cinched around the head.
Credit: Justin Simoni

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 Katabatic Gear Flex 22 Quilt came out on top. It uses more fill— 15.4 ounces — but this down is of a lower fill power and quality: 850 duck down. This quilt is more versatile, and for those nights you don't need so much insulation, you can turn it into a blanket rather than struggle to get comfortable sweltering in a sleeping bag. The Outdoor Vitals StormLoft Down TopQuilt also scored well but didn't meet our expectations for its labeled 15°F limit rating. To get the most out of the temperature rating of this bag, it's imperative that you pair this quilt with a down balaclava and warm sleeping pad, as both these influence just how toasty you're going to feel while snoozing.

ultralight sleeping bag - a must-have accessory for a quilt with a limit rating of 15f - like...
A must-have accessory for a quilt with a limit rating of 15F - like the Outdoor Vitals StormLoft, is a proper insulated balaclava which complements the quilt and keeps your head as insulated as your body.
Credit: Justin Simoni

The Zpacks Classic hoodless sleeping bag also scored well, with an incredible 13.1 ounces of 900 fill goose down used for this 19.8-ounce bag. The insulation makes up a whopping 66% of this bag's weight! You will want to grab an insulated hat to complement this bag, as there is no hood.

ultralight sleeping bag - if you&#039;re after the lightest ultralight bag that&#039;s warm enough for...
If you're after the lightest ultralight bag that's warm enough for three-season use and thru-hikes, the Zpacks Classic is an excellent choice.
Credit: Brandon Lampley

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 being willing to make some compromises in comfort or convenience, ultralighters can enjoy the considerable benefits of a lighter 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 product's price.


When it comes to ultralight sleeping bags, most manage 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.

ultralight sleeping bag - not all ul sleeping bags pack down equally!
Not all UL sleeping bags pack down equally!
Credit: 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. Zippers are also often shortened to trim ounces at the sacrifice of venting possibilities. Most ultralight mummy bags have rather narrow dimensions because less fabric is needed so that the bag can be further lightened.

ultralight sleeping bag - if venting is important to you, choosing a bag with a zip, like the...
If venting is important to you, choosing a bag with a zip, like the Spark Ultralight 28, can make a huge difference.
Credit: Justin Simoni

We weighed these bags on an independent scale to determine the weight and then assigned the scores comparatively. In the case of quilts requiring extra straps or buckles 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.

ultralight sleeping bag - we weighed every sleeping bag, with and without the stuff sack, to...
We weighed every sleeping bag, with and without the stuff sack, to see which lives up to its ultralight title.
Credit: Justin Simoni

A surprising front-runner for the lightest bag is the Therm-a-Rest Vesper 32 quilt, coming in at only 15 ounces! It only has nine ounces of 900 goose down fill, which compromises a good 60% of the total bag's weight, so it isn't going to be the warmest bag. The Western Mountaineering's HighLite sleeping bag also scored high in low weight, coming in at 15 ounces. Being a bag, it has less fill in total, eight ounces, making up 53% of the bag's weight. It throws many ultralight tricks at the problem of shaving grams, including using lofty, 850+ down, half zips, and thin fabric material.

ultralight sleeping bag - cowboy camping in utah with the vesper 32.
Cowboy camping in Utah with the Vesper 32.
Credit: Ethan Newman

A more unique flyweight design weighing in at 16.2 ounces is found in the Feathered Friends Vireo UL, which is designed to have far less warmth in the top portion of the bag to then be supplemented with an additional insulation layer you're already packing, while also cutting features to almost nothing, including a lack of zipper, nor a hood! This design decision follows the ultralight ethic of prioritizing items that have multiple uses to save weight across your entire pack system.
ultralight sleeping bag - the vireo holds more down at the feet as it is designed to be paired...
The Vireo holds more down at the feet as it is designed to be paired with a jacket.
Credit: Justin Simoni

The Big Agnes Fussel UL Quilt, Western Mountaineering AstraLite, and Sea to Summit Spark Ultralight 28 follow closely behind, all weighing in the mid-17-ounce range. The Fussel and AstraLite are both quilt-style bags that have 850 fill. The Spark 28 packs in 850 RDS ultra dry goose down to its 10D nylon shell.

ultralight sleeping bag - the fussell is great for sunset watching and cozying up around the...
The Fussell is great for sunset watching and cozying up around the campsite, thanks to its versatile quilt-style.
Credit: Justin Simoni

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 loathing getting into a subpar sleeping bag or quilt, which is why comfort is important enough to make it 20% of the overall score.


When assessing for comfort, the first thing we looked at was 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 could compare each bag's fit to the same standard. Luckily for you, most of the bags in this review come in different height and width options, making 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.

ultralight sleeping bag - waking up to a chilly morning after sleeping out in the san juan...
Waking up to a chilly morning after sleeping out in the San Juan Mountains. The Vireo, in blue, and the HighLite in purple.
Credit: Jenna Ammerman

Rather than reduce the length, most ultralight quilts 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, which is good news, as it lacks a zipper. Quilts, on the other hand, offer plenty of room but sometimes yield claustrophobic feelings when we utilize their pad attachment systems. Some quilts were too narrow to wrap ourselves in on chillier nights, no matter how much we repositioned.

ultralight sleeping bag - the vireo has a generous opening and width, perfect for those who...
The Vireo has a generous opening and width, perfect for those who like to toss and turn or sleep curled up.
Credit: Justin Simoni

On top was the Therm-a-Rest Hyperion 20. For a mummy bag, it features a fairly generous girth throughout the bag - enough for our main tester's more-than-average shoulders. Many other mummy bags are too constricting and may make you wonder if you're getting prepped to be buried alive. Many other bags/quilts scored just a little lower, including the Western Mountaineering Astralite, which had a standout feature of utilizing a generous draft yoke around the neck to really stop any cold air from coming in. It almost felt like a pillow for the front of your head!

ultralight sleeping bag - the unique draft yoke of the western mountaineering astralite was...
The unique draft yoke of the Western Mountaineering Astralite was one of our favorite features of the quilt.
Credit: Justin Simoni

None of the other top models of sleeping bags/quilts we tested had outstanding comfort scores. This doesn't mean they're uncomfortable, but it highlights that comfort compromises 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 are too much, consider a more traditional backpacking sleeping bag.

Related: Best Backpacking Sleeping Bag of 2024

ultralight sleeping bag - watching the last rays of the day is always better bundled up!
Watching the last rays of the day is always better bundled up!
Credit: Justin Simoni

Versatility


If you want a three-season sleeping bag or are planning an epic six-month thru-hike that will span the seasons from a cool spring into a 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 sleeping bags that used synthetic insulation, which will not clump and will continue to provide substantial insulation even when wet, received a bonus.

ultralight sleeping bag - 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 bikepacking, 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.

ultralight sleeping bag - 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.
Credit: Andy Wellman

No question, the most versatile ultralight sleeping bag we tested 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 40°F version of this bag, it also comes in 30°F and 20°F versions for those who live and play in colder climates or seasons.

Easily transform the Flicker 40 from a sleeping bag mode to an open blanket.
Credit: Justin Simoni

Also scoring well for its versatility are the Feathered Friends Hummingbird UL 30 and Zpacks Classic. The Hummingbird UL is filled with 950+ goose down and keeps warmth from its horizontal baffles and hood. For those warmer nights, the full-length zip helps dump heat. The Zpacks Classic is a hoodless mummy bag rated to 20°F with a box baffle construction and a DWR-coated Pertex Nylon shell. It's ideal for cold nights. It also has a ¾ length zipper, so you can open it up like a quilt for warmer nights.

ultralight sleeping bag - 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, and hoods are all designed to enhance a sleeping bag's 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.

ultralight sleeping bag - the hyperion 20 has a two-way zip and top snap, so you can easily...
The Hyperion 20 has a two-way zip and top snap, so you can easily dump heat without your head getting exposed.
Credit: Justin Simoni

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. The Feathered Friends Hummingbird tries to solve many of those annoying zipper problems by employing a flexible piece of plastic by the zipper, to stop the fabric from being sucked into the zipper and stuck.

ultralight sleeping bag - the handy anti-snagging zipper of the feathered friends hummingbird...
The handy anti-snagging zipper of the Feathered Friends Hummingbird helps this bag smoothly open and close.
Credit: Ian McEleney

The Feathered Friends Flicker 40 UL 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, and 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.

The uncinched footbox of the Hammock Gear Economy Burrow.
The uncinched footbox of the Hammock Gear Economy Burrow.
The Hammock Gear Economy Burrow cinched footbox.
The Hammock Gear Economy Burrow cinched footbox.
Many quilts feature a transformable footbox that allows you to choose how enclosed they are, which really helps in modulating heat retention.

Many quilts have a variety of shared features that allow you to transform them from a quilt with a footbox to a flat blanket using a series of snaps, straps, and zippers. Find them in the Enlightened Equipment Revelation 20, the Enlightened Equipment Revelation APEX 30, the Katabatic Gear Flex 22 Quilt, and the Hammock Gear Economy Burrow 20.

ultralight sleeping bag - 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


Sleeping bags have been around for a long time, and the market is flush with options for use in or outside of a tent. 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 the world of backpacking is only getting leaner as companies shave down the ounces in their gear and people start appreciating a faster and lighter approach. 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 bags are for people who want to move quickly through the mountains without the added weight of a bulky bag. 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. With our extensive comparison of the best models of ultralight sleeping bags and quilts on the market, we hope you find the right choice for your backcountry adventures.

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