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

The Best Backpacking Sleeping Bags of 2019

Sunday May 12, 2019
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To help you score the best backpacking sleeping bag, we researched more than 100 of the latest models and selected 14 top models to undergo rigorous, hands-on testing. Our reviewers then shivered and sweat through countless nights, from the snowy summits of the Sierra Nevada to the sweltering desert of Death Valley. Your sleeping bag is one of the most important parts of your overnight kit. And finding the right one ain't easy. The findings we share below are sure to make your next backcountry adventure warmer, cozier, and easier.

Related: Best Sleeping Bags for Women


Top 14 Product Ratings

Displaying 1 - 5 of 14
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Awards Editors' Choice Award Top Pick Award Top Pick Award  Best Buy Award 
Price $470.00 at Backcountry
Compare at 2 sellers
$430 List$510.00 at Backcountry
Compare at 2 sellers
$389.00 at Feathered Friends$199.95 at REI
Compare at 3 sellers
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Pros Spacious dimensions, super comfortable, great loft, lightweight, made in the USASuper lightweight, incredible loft, snag-proof zipper, cozy hoodBest-in-class warmth, legit draft collar, light weight, exceptional loftBest-in-class zipper, best-in-class hood, awesome loft, great warmth-to-weight ratioAwesome warmth-to-weight ratio for the price, very compressible, tons of venting options, nice compression sack included
Cons Expensive, awkward hood, good but not great zipperUncomfortably narrow dimensions, bare-bones design, noisy fabricReally pricey, kind of bulky, awkward hood closureNarrow leg dimensions, no draft collar, heavier and bulkier than some 3-season optionsNot as warm as its temp rating, no draft collar, uncertain durability
Bottom Line The only ultra-premium bag to combine low weight, good packability, and luxurious comfort.Our favorite when ounces matter, this is a full-size mummy bag that's both warm and ultralight.A ultra-premium bag that's our favorite for cold nights in spring and fall.Our favorite zipper and hood in a bag that's also exceptionally warm and lofty.An exceptional deal for a lightweight bag that excels in wet conditions.
Rating Categories MegaLite Merlin 30 UL UltraLite Swallow 20 YF NEMO Kyan 35
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Specs MegaLite Merlin 30 UL UltraLite Swallow 20 YF NEMO Kyan 35
Insulation 850+ FP Down 950+ FP Down 850+ FP Down 900+ FP Down Synthetic - Primaloft Silver
Compressed Volume (L) 7.2 L 7.3 L 8.7 L 8.5 L 6.6 L
Measured Bag Weight (Size Long) 1.62 lbs 1.45 lbs 1.86 lbs 1.94 lbs 1.89 lbs
Compression/Stuff Sack Weight (oz) 1.6 oz 0.8 oz 1.6 oz 1 oz 2.4 oz
Manufacturer claimed weight of size Regular (lbs) 1.5 lbs 1.33 lbs 1.81 lbs 1.79 lbs 1.69 lbs
Hydrophobic down No No No No N/A
Manufacturer Temp Rating (F) 30 30 20 20 35
EN Temp Rating (Lower Limit) Not rated Not rated Not rated Not rated 35
Fill Weight (oz) 13 12 17 17.5 12
Shell material Extremelite (12D) Pertex Endurance (10D) Extremelite (12D) Pertex YFuse (20D) Ripstop nylon (20D)
Neck Baffle No No Yes No No
Small Organization Pocket No No No No Yes
Zipper Full-length / Side Full-length / Side Full-length / Side Full-length / Side 3/4-length / Side
Shoulder Girth (in) 64 58 59 60 62
Hip Girth (in) Unknown 52 Unknown 56 57
Foot Girth (in) 39 38 38 38 46
Compression or stuff sack included? Stuff Stuff Stuff Stuff Compression

Best Overall Model


Western Mountaineering MegaLite


Editors' Choice Award

$470.00
(3% off)
at Backcountry
See It

80
OVERALL
SCORE
  • Warmth - 20% 8
  • Weight - 20% 8
  • Comfort - 20% 9
  • Packed Size - 15% 8
  • Versatility - 15% 7
  • Features & Design - 10% 7
Weight: 1.63 lbs | Fill Power: 850+ Goose Down
Spacious fit
Luxurious loft
Warmer than its 30°F rating
Great warmth-to-weight ratio
Pricey
Awkward hood closure

The MegaLite is our favorite backpacking sleeping bag because it performs well in all areas. Like other ultra-premium down bags, it offers an outstanding warmth-to-ratio in a bag that packs down extremely small. Unlike the other ultra-premium down bags we tried, it features spacious interior dimensions that supply superior comfort no matter you're sleeping style. For virtually any overnight backcountry application this is an excellent choice.

Our performance criticisms are minor—the hood closure is slightly awkward, and its zipper is good, but not great. A more significant issue is its price. The MSRP is likely to dissuade more than a few shoppers. We feel, however, the considerable benefits of this and other high-end down bags are worth the exorbitant costs for dedicated users, especially when you factor in the outstanding longevity of their loft. The hard choice, then, is deciding between the MegaLite—our favorite bag for the average backpacker—and other top-performers, like the Feathered Friends Merlin UL and Western Mountaineering UltraLite, which may be better suited for some specialty applications.

Read review: Western Mountaineering MegaLite

The Best Deal and The Best for Wet Conditions


NEMO Kyan 35


69
OVERALL
SCORE
  • Warmth - 20% 3
  • Weight - 20% 7
  • Comfort - 20% 7
  • Packed Size - 15% 9
  • Versatility - 15% 9
  • Features & Design - 10% 8
Weight: 1.89 lbs | Insulation: 12 oz of Primaloft Silver
Packs super small
Retains significant warmth when wet
Great price for its warmth-to-weight ratio
Includes a functional compression sack
Doesn't live up to its 35°F rating
Weak loft

As a general rule, sleeping bags with synthetic insulation are larger and heavier than their down counterparts. Somebody forgot to tell the Nemo Kyan 35. It shocked us with its moderate and weight and tiny packed size that was on par with several down bags at the same temperature rating. Also, its Primaloft Silver synthetic insulation is a much better choice for wet conditions because it retains a significant percentage of its warmth even when soaked. The cherry on top is the more than reasonable price tag.

The Kyan 35 attributes some of its low weight and small packed size to the lower insulation requirements for its 35°F temperature rating. In the field, our testers felt for this bag, even this rating was a little generous. We thus only recommend the Kyan for warmer 3-season conditions. Nemo, however, offers a 20° version that appears on paper to provide similarly high performance for colder situations. Despite its warmth deficiency, the Kyan 35 is an excellent bag at a price that can't be beaten.

Read review: Nemo Kyan 35

Best Budget Down Bag


Kelty Cosmic 20


Best Buy Award

$159.95
(6% off)
at REI
See It

54
OVERALL
SCORE
  • Warmth - 20% 6
  • Weight - 20% 3
  • Comfort - 20% 6
  • Packed Size - 15% 6
  • Versatility - 15% 6
  • Features & Design - 10% 6
Weight: 2.63 lbs | Packed Size: 8.7 liters
Very affordable
Decent weight and packed size
Suitable for backpacking
Burly materials
Low warmth-to-weight ratio
Below average comfort
No compression or storage sack included

Although the Kelty Cosmic 20 scores near the bottom of the field, it was up against many ultra-premium bags that cost up to three times more. Sure, those bags are a lighter and they pack smaller, but you can sleep just as well inside the Cosmic using all the money you saved as a pillow. For a low price, you get a sleeping bag that supplies respectable levels of warmth and comfort at a weight and size that's still reasonable for backpacking. You also get the convenience of a stash pocket and coziness of a neck baffle—two features that are missing on many of its more expensive rivals.

The Cosmic cuts its costs by using a mixture of 600 fill power down (83%) and synthetic fibers (17%) for insulation. This results in a bag that's a pound heavier and two liters larger inside your pack than comparably warm, 100% premium down bags. With the money you save, however, you can invest in a better tent or sleeping pad to reduce the weight and volume of your overall backcountry kit.

Read review: Kelty Cosmic 20

Top Pick for Fast and Light Adventures


Feathered Friends Merlin 30 UL


Top Pick Award

$430 List
List Price
See It

79
OVERALL
SCORE
  • Warmth - 20% 8
  • Weight - 20% 9
  • Comfort - 20% 7
  • Packed Size - 15% 8
  • Versatility - 15% 8
  • Features & Design - 10% 7
Weight: 1.45 lbs | Fill Power: 950+ Goose Down
Exceptional warmth-to-weight ratio
Best loft in the review
Exceptional anti-snag zipper
Comfy hood
Narrow fit
Expensive
Noisy shell fabric

When saving weight takes precedence over everything else, one of our favorite bags is the Merlin UL. Feathered Friends uses the highest fill power down we've tried (950+) to create a bag that is exceptionally warm yet truly ultralight. Somehow this bag also manages to include a sturdy full-length zipper that's virtually immune to snagging. The same zipper provides ample venting options and the possibility of sharing it as a quilt with a partner during a full-on bivouac.

Although we're big fans, the Merlin UL achieves its low weight with its particularly narrow dimensions that many will find constrictive. Its ultra-high fill power down also comes with an ultra-high list price. If you look past these faults, however, you get a traditional sleeping bag that offers an unparalleled warmth-to-weight ratio. There may be no better choice when the ounces matter.

Read review: Feathered Friends Merlin 30 UL

Top Pick for Colder 3-Season Conditions


Western Mountaineering UltraLite


Western Mountaineering UltraLite
Top Pick Award

$510.00
at Backcountry
See It

76
OVERALL
SCORE
  • Warmth - 20% 10
  • Weight - 20% 7
  • Comfort - 20% 7
  • Packed Size - 15% 6
  • Versatility - 15% 8
  • Features & Design - 10% 7
Weight: 1.86 lbs | Fill Power: 850+ Goose Down
Warmest bag in the review
Sturdy full-length zipper
Legit draft collar
Continuous horizontal baffles
Super expensive
Maybe too warm
Bulky packed size

If you know you "sleep cold" or you've got plans for higher elevation trips in the spring or fall, the Western Mountaineering UltraLite might be the best bag for you. With its 17 ounces of 850+ fill power down and legit draft collar, our testers thought it was easily the warmest bag in the review. Also, its full-length zipper and continuous horizontal baffle construction allow enough venting possibilities to avoid overheating on hot summer nights. In the field, we were able to sleep comfortably in this bag across an impressive range of overnight temperatures from 10° to 55°F.

The drawback to this exceptional performance is a staggering price tag. We also believe that most 3-season travelers would be happier with a slightly less warm bag that can offer weight and packed size benefits. Nevertheless, if you're looking for an awesome bag that's assured to keep you toasty, the UltraLite is our favorite offering.

Read review: Western Mountaineering UltraLite

Top Pick for Exceptional Comfort


Sierra Designs Backcountry Bed 700


Top Pick Award

$279.95
at Backcountry
See It

66
OVERALL
SCORE
  • Warmth - 20% 5
  • Weight - 20% 5
  • Comfort - 20% 9
  • Packed Size - 15% 8
  • Versatility - 15% 6
  • Features & Design - 10% 7
Weight: 2.10 lbs | Insulation: 700 Fill Power Dridown
Zipperless comforter-like closure
Roomy dimensions
Convenient foot vent
Great for tummy sleepers
Heavy for its warmth
Drafty in colder weather
Medium-quality down

This bag lives up to its name by bringing the comfort of an ordinary bed to the backcountry. Its zipperless design features a comforter-like flap that you can fold open or close to get your temperature just right. The notably roomy dimensions also mimic the freedom of movement you have with a regular blanket, ensuring you have plenty of space to stretch your legs or roll over.

The drawback to this exceptional comfort is the extra materials that are needed which add weight and bulk to the overall bag. Its 35°F temperature rating also felt a little optimistic, so we suggest "cold sleepers" consider the Sierra Designs Cloud 20 for regular use in spring or fall. Nevertheless, with the Backcountry Bed, Sierra Designs has created an exceptionally comfortable bag that is sure to be adored by those who've long found the design of traditional sleeping bags unpleasant.

Read review: Sierra Designs Backcountry Bed 700


Sleeping bags offer the highest warmth-to-weight ratio of any outdoor gear so a good bag should be one of the most important pieces of your overall overnight kit.
Sleeping bags offer the highest warmth-to-weight ratio of any outdoor gear so a good bag should be one of the most important pieces of your overall overnight kit.

Why You Should Trust Us


Lead author Jack Cramer is an accomplished climber, a National Outdoor Leadership School alumnus, and undeniable gear nerd. Co-author Ian Nicholson is an American Mountain Guides Association-certified guide who has helped over 1,000 clients select the right gear for backpacking, climbing, and ski trips. Although they've both spent the better part of the last decade in the backcountry, they consulted with Appalachian and Pacific Crest Trail thru-hikers, Yosemite Search and Rescue team veterans, sponsored outdoor athletes, and novice backpacker friends to ensure this review contained a diverse set of perspectives. The result is a review that's designed to be useful for a wide variety of backcountry activities across all types of conditions.

In this quest, our review team researched more than 100 of the most popular backpacking sleeping bags. We've tested scores of backpacking models over the years. Here, we selected and purchased 14 of the best today's market has to offer to undergo extensive testing. We measured warmth, weight, and packed size in the lab. The remaining performance characteristics, such as comfort, versatility, and design, were assessed in the spectacular landscapes of the Sierra Nevada, southern Utah wilderness, and Death Valley National Park. Bags went to elevations from -150 to 12,000 feet with nighttime lows between 10° and 65°F.

Recording our thoughts during a field test with the Feathered Friends Merlin.
We stuffed all the sleeping bags we tested  including this Western Mountaineering UltraLite  into this Granite Gear 11-liter compression sack and then measured the dimensions to calculate compressed volume.
The authors of the our backpacking sleeping bag reviews with a pile of several million goose feathers.

This review is also unique because it includes direct comparisons between Western Mountaineering and Feathered Friends products. Small specialty manufacturers make some of the best down gear on the market, but their reluctance to give reviewers their products for free limits how many get reviewed. Fortunately, OutdoorGearLab's policy of purchasing all the sleeping bags we test gives us the flexibility to include both makers in this comprehensive review.

Related: How We Tested Backpacking Sleeping Bags

Analysis and Test Results


Designing a great sleeping bag is a tricky balancing act. Add extra insulation to make it warmer, and it quickly becomes too heavy. Trim the zipper's length to save weight, and you limit your options for venting excess heat. Therefore, to evaluate bags fairly, we selected six performance criteria that are undeniably important but often at odds with one another: warmth, weight, comfort, packed size, versatility, and features & design. Below we examine each criterion more closely and highlight the top performers.

Related: Buying Advice for Backpacking Sleeping Bags

The Nemo Kyan impressed us with its outstanding performance and surprisingly low price ($200 list). We consider it one of the best sleeping bag deals out there.
The Nemo Kyan impressed us with its outstanding performance and surprisingly low price ($200 list). We consider it one of the best sleeping bag deals out there.

Value


Although the price is not a consideration in our performance scores, we know it's important to your purchasing decision. Sleeping bags, in particular, come in a surprisingly wide range of prices for different models that ostensibly serve the same purpose. After extensive testing, however, we can confidently say that the price differences generally reflect meaningful performance differences.


In terms of absolute performance, nothing came close to the Feathered Friends and Western Mountaineering bags which demonstrated clear superiority in overall design, build quality, and warmth-to-weight ratios. These bags, however, require most of us to save up to afford them. For less than half the price of these premium bags, the Nemo Kyan 35 or Kelty Cosmic 20 both offer exceptional deals. Although they're a little heavier and bulkier, once you get them to camp, you're likely to sleep just as well.

Warmth


Your warmth in a bag is largely a function of the quantity and quality of the insulation. With down bags, you can get a rough sense of their warmth by examining the fill weight (quantity) and fill power (quality) of the down it contains. This task is trickier with synthetics where the overwhelming number of proprietary fibers makes comparison close to impossible. Further complicating matters is the design and fit of a bag which has a smaller, but still significant, effect on its warmth.


In attempt to resolve this confusion, the European Union developed EN 13537, an industry-standard test designed to provide sleeping bag temperature ratings that are consistent between different companies. Although these EN ratings seem to be more accurate than other warmth indicators, some of the best manufacturers chose not to have their bags tested. Also, the details of the testing protocols can arbitrarily favor certain designs that may not reflect real-world warmth.

The EN comfort  lower limit  and extreme temperature ratings listed on the Therm-a-Rest Hyperion. Our testers don't think it's quite as warm as these ratings.
The EN comfort, lower limit, and extreme temperature ratings listed on the Therm-a-Rest Hyperion. Our testers don't think it's quite as warm as these ratings.

Due to these issues, we chose to evaluate warmth using real human testers. To keep things fair, we slept in each bag for at least three nights in a 48°F room. The performance was then assessed relative to the other bags we tried and their EN ratings if they had one. The difference between the warmest and coldest bags was much more significant than the official ratings would suggest. The same field tester, for example, slept comfortably in a Western Mountaineering UltraLite at temperatures 10° below its 20°F rating, and shivered in the Nemo Kyan 35 in temperatures 10° above its 35°F rating.

In climbing and mountaineering  and perhaps even more than long-distance hiking  weight is an important factor. You may have to make challenging technical moves with the weight of your sleeping bag on your back. Photo: An open bivy with the MegaLite under the stars while climbing the North Ridge of Forbidden Peak.
In climbing and mountaineering, and perhaps even more than long-distance hiking, weight is an important factor. You may have to make challenging technical moves with the weight of your sleeping bag on your back. Photo: An open bivy with the MegaLite under the stars while climbing the North Ridge of Forbidden Peak.

Our warmth ratings scale so that a score of ten indicates bags with the highest level of warmth, and a one, the least. Importantly, this doesn't mean that a bag with a ten would be the best possible bag for you. More likely, if you're looking for a bag for moderate 3-season conditions, a 7 or 8 will probably be sufficient. For most people, the bags with the highest warmth rating are better-suited for the colder nights of spring and fall.

While sleeping bags are foundational to staying warm during overnight stays in the backcountry  100% of sleeping bags are designed to be used in conjunction with a sleeping pad and no model will perform anywhere close to its published rating without one.
While sleeping bags are foundational to staying warm during overnight stays in the backcountry, 100% of sleeping bags are designed to be used in conjunction with a sleeping pad and no model will perform anywhere close to its published rating without one.

Keep in mind that for your bag to keep you warm down to its temperature rating you will also need a quality sleeping pad and protection from the elements.

Related: The Best Backpacking Sleeping Pads of 2019

Related: The Best Backpacking Tents of 2019

Weight


In contrast to warmth, weight is easy to measure objectively. For human-powered activities weight also happens to be one of the most important considerations. A sleeping bag's weight is a consequence of the amount and type of insulation, the dimensions of the bag, the size and length of the zipper, and the density of the fabrics. Generally, higher quality materials weigh less but come with correspondingly high prices. Saving weight with a shorter zipper or trimmer fit is also an option but comes with figurative costs in terms of versatility or comfort.


To evaluate weight we used our digital scale to weigh each bag. Separately we also weighed the included stuff and compression sacks. Our 'Weight' performance category, however, is based solely on the weight of the bag under the assumption that most users will get their own after-market compression sack that is lighter and more effective at compression.

Take ultralight principles to the extreme and it's possible to trim enough weight off your overnight pack to enjoy activities like climbing  skiing  or backpacking for weeks on end.
Take ultralight principles to the extreme and it's possible to trim enough weight off your overnight pack to enjoy activities like climbing, skiing, or backpacking for weeks on end.

There was almost a 1.5-pound difference between the lightest and heaviest bags in this review—the Therm-a-Rest Hyperion 32 and the Kelty Cosmic 20, respectively. This difference may not sound like much, and perhaps for a single piece of gear, it's not. However, if you have the means and wherewithal to combine a 1.5 pound in weight savings on your sleeping bag with comparable weight savings on your tent, sleeping pad, and cook kit the difference becomes enormous.

The Merlin is our favorite backpacking sleeping bag for when we want to go light. Pair it with a backpacking tarp to really trim the weight of your overnight kit.
The Merlin is our favorite backpacking sleeping bag for when we want to go light. Pair it with a backpacking tarp to really trim the weight of your overnight kit.

Premium ultralight bags, like our favorite Feather Friends Merlin UL, thus become one piece in the puzzle that is cutting 10-15 pounds from your load. Accomplishing this is unfortunately expensive but doing so pays enormous dividends in terms of your back/knee health and overall enjoyment.

Comfort


To sleep well, you have to be comfortable. Most find this easy to achieve in a bed with a blanket and a thermostat nearby. The task can be harder outdoors when you're at the mercy of mother nature and zipped inside an ill-fitting sack. Although some people can sleep like a log in any sleeping bag, many find the unfamiliar and inherently restrictive design to be disruptive. The former group can ignore this performance category, but the latter should devote special attention.


To evaluate comfort, we considered several factors: the dimensions and fit of a bag, the loft of the insulation, the feel of the interior fabric, and in some cases, the noisiness of the materials. Although being too cold or warm can obliviously affect your comfort, we tried to evaluate the likelihood of this happening with our separate warmth and versatility metrics. A bag's comfort score is thus our best subjective judgment of its performance in the fit, loft, feel, and noisiness.

The symmetrical "comforter" on the Sierra Designs Backcountry Bed can be closed to seal heat in (top) or opened to let heat escape (bottom).
The symmetrical "comforter" on the Sierra Designs Backcountry Bed can be closed to seal heat in (top) or opened to let heat escape (bottom).

Three bags provided notably impressive comfort in three different ways that are worth discussing. The Sierra Designs Backcountry Bed is perhaps the most interesting of these. Its zipperless design incorporates a comforter-like flap that mimics the feel of an ordinary bed and blanket. This design, however, lacks a reliable closure mechanism so it could feel a bit drafty. Avoid this issue with the similarly comfortable Nemo Riff 30. It features a ¾-length zipper like a classic mummy bag but contours like a broad hour-glass instead of a tapered sarcophagus. The bottom of the hour-glass provides ample room for side and tummy sleepers to stretch their legs in any direction.

The lofty Western Mountaineering MegaLite (left)  hourglass-shaped Nemo Riff (center)  and zipperless Sierra Designs Backcountry Bed (right) all achieve their exceptional comfort in different ways.
The lofty Western Mountaineering MegaLite (left), hourglass-shaped Nemo Riff (center), and zipperless Sierra Designs Backcountry Bed (right) all achieve their exceptional comfort in different ways.

While we enjoyed the Riff's innovative shape, its down is not particularly lofty, nor is its fabric exceptionally soft. The final stand out in the comfort department, the Western Mountaineering MegaLite addressed these deficiencies. Its 850+ fill power down and 12-denier ExtremeLite fabric team up to create a cozy cocoon of luxurious loft. Although it's among the most spacious models, it has a classic mummy shape that won't be appreciated by all.

Check out the difference between budget down and ultra-premium. The 850+ FP down of the MegaLite (right) lofts 6 inches upward  while the KSB's 650 FP down (left) lays nearly flat on the ground.
Check out the difference between budget down and ultra-premium. The 850+ FP down of the MegaLite (right) lofts 6 inches upward, while the KSB's 650 FP down (left) lays nearly flat on the ground.

As these examples illustrate, a bag's comfort is inherently subjective, so it's essential to choose one that matches your preferences. Those that don't detest mummy bags will likely prefer the MegaLite's luxurious materials. Meanwhile, side sleepers may find the Riff's innovative shape superior. Finally, if zipping yourself inside a bag always made you feel claustrophobic, the Backcountry Bed may be your salvation.

Bags in their included stuff sacks. From left to right  top row: Therm-a-Rest Hyperion  Nemo Kyan  Nemo Rff  Mountain Hardwear Lamina  Feathered Friends Merlin  Feathered Friends Swallow. Bottom row: Western Mountaineering UltraLite  Western Mountaineeering MegaLite  Sierra Designs Cloud  Sierra Designs Backcountry Bed  Rab Mythic  Marmot Phase 20  REI Igneo.
Bags in their included stuff sacks. From left to right, top row: Therm-a-Rest Hyperion, Nemo Kyan, Nemo Rff, Mountain Hardwear Lamina, Feathered Friends Merlin, Feathered Friends Swallow. Bottom row: Western Mountaineering UltraLite, Western Mountaineeering MegaLite, Sierra Designs Cloud, Sierra Designs Backcountry Bed, Rab Mythic, Marmot Phase 20, REI Igneo.

Packed Size


The bigger your backpack, the further away its weight is from your center of gravity, the harder it is to carry, the more fatigued you get, the less fun you have. Sleeping bags occupy a significant portion of an overnight backpack. Therefore, getting a bag that compresses smaller can be an effective way to reduce the size, and burden, of your overall load.


All the bags we tested included some stuff or compression sack for storing them inside your backpack. Many of these sacks, however, were unable to compress a sleeping bag fully. So to evaluate packed size we used the same 11-liter Granite Gear compression sack to measure each bag's minimum compressed volume.

The Feathered Friends Swallow stuffed in an after-market compression sack (left) and the stuff sack that it comes with (right).
The Feathered Friends Swallow stuffed in an after-market compression sack (left) and the stuff sack that it comes with (right).

By and large the compressed volumes we observed corresponded closely with the weight of each bag. A couple of exceptions were the Nemo Kyan 35, which compressed roughly 20% more than its weight would suggest, and the Marmot Phase 20 and Western Mountaineering UltraLite, which were 15% larger than comparably heavy bags.

The Nemo Kyan 35 (left) weighs nearly the same as the Western Mountaineering UltraLite 20 (right) but compresses a lot smaller. The UltraLite  however  is substantially warmer.
The Nemo Kyan 35 (left) weighs nearly the same as the Western Mountaineering UltraLite 20 (right) but compresses a lot smaller. The UltraLite, however, is substantially warmer.

Although these discrepancies are worth noting, we consider all the bags we tested to be small, especially when compared to The Best Budget Backpacking Sleeping Bags or the bags of yesteryear. Therefore, we don't think packed size is a great characteristic for distinguishing between the nicer backpacking sleeping bags. Depending on your budget, however, it may be worth checking if the bag you're thinking of getting includes a functional compression sack. If not, a quality after-market compression sack will set you back a few dollars.

Related: The Best Budget Backpacking Sleeping Bags of 2019

Versatility


Versatility speaks to how useful a piece of gear is for a variety of activities and conditions. For sleeping bags, we assessed it by considering the range of temperatures a bag is comfortable in, how well it performed if it got wet, and whether a bag does things besides keeping a single person warm when sleeping.


How comfortable a bag is in a range of temperatures is determined by its ability to insulate at lower temperatures and its ability to vent excess heat at higher temperatures. Draft collars and well-fitting hoods are both features that boost a bag's cold weather performance, such as those found on the Western Mountaineering UltraLite. Conversely, a long main zipper and accessory vents extend the Nemo Riff 30's performance on warmer nights.

The venting "gills" on the top of the Nemo Riff 30 with zippers closed and open.
The venting "gills" on the top of the Nemo Riff 30 with zippers closed and open.

Overall, the bags with ¾- or full-length zippers seem to supply adequate venting options for most 3-season conditions. However, the shorter half-length zippers of the Rab Mythic 400 and Therm-a-Rest Hyperion 32 make sleeping in average summer temperatures far less pleasant.

The makers of all these bags call the zippers "full-length" but there is a noticeable difference between the Nemo Kyan (orange)  Western Mountaineering UltraLite (blue)  and Feathered Friends Swallow (red).
The makers of all these bags call the zippers "full-length" but there is a noticeable difference between the Nemo Kyan (orange), Western Mountaineering UltraLite (blue), and Feathered Friends Swallow (red).

How well a bag performs when wet is primarily determined by its type of insulation. Down notoriously clumps and loses its ability to insulate if it gets wet. Synthetic fibers, in contrast, do not clump and can continue to supply up to 50% of their usual warmth when soaked. For this reason, synthetic bags, like the Nemo Kyan 35 and Mountain Hardwear Lamina 35, are better choices for particularly wet activities or environments.

The Nemo Kyan's synthetic insulation is ideal if you're worried about rain getting your sleeping bag wet.
The Nemo Kyan's synthetic insulation is ideal if you're worried about rain getting your sleeping bag wet.

Many manufacturers now market their down as hydrophobic because it receives a chemical treatment to improve water resistance. Claims about the performance benefits of these treatments are often overstated. In our testing, we observed little difference between down that was treated or untreated, so it didn't factor into the versatility score. Interestingly, both of the top performing bag makers, Western Mountaineering and Feathered Friends, do not use any hydrophobic down due to concerns about the longevity of the chemical treatments and possible harm to the water-resistant oils that high-quality down naturally contains.

We didn't identify any substantial difference in performance between hydrophobic and non-hydrophobic down. Both performed equally bad when wet. So if you're expecting rain take every precautions to keep your down bag dry or use synthetic insulation instead.
We didn't identify any substantial difference in performance between hydrophobic and non-hydrophobic down. Both performed equally bad when wet. So if you're expecting rain take every precautions to keep your down bag dry or use synthetic insulation instead.

The final aspect of versatility is whether a bag can work in other ways. We found bags with particularly long zippers, like the Feather Friends Merlin 30 UL and Swallow 20 YF, could be shared as a quilt when fully unzipped, which is a nice bonus when eating breakfast on a cold morning or during an unplanned bivouac.

Bags with truly full-length zippers  like the Feathered Friends Swallow  can be zipped open to share as a quilt on really cold mornings.
Bags with truly full-length zippers, like the Feathered Friends Swallow, can be zipped open to share as a quilt on really cold mornings.

Features and Design


Features and Design is a catch-all category to encompass the performance characteristics not addressed with other evaluation criteria. 'Features' includes things like small stash pockets, sleeping pad attachment systems, and the quality of the bag's zipper, among other things. 'Design' assesses the overall execution of the bag. Are all of its materials similarly durable? Do its warmth weight, and dimensions make sense for its intended application?


One unique feature we like is the waterproof fabric on the footbox of the Nemo Riff 30, which ensures the bag's down insulation doesn't become saturated from brushing against condensation on a tent wall. We are also big fans of the full-length zippers on the Feathered Friends bags. Not only do they feature a Y-shaped, anti-snag slide, but there is an internal strip of plastic in the fabric next to the teeth that further reduces the chance of snagging.

The Feathered Friends bags that we tried feature a Y-shaped zipper slide and an internal strip of flexible plastic to prevent the zipper from snagging.
The Feathered Friends bags that we tried feature a Y-shaped zipper slide and an internal strip of flexible plastic to prevent the zipper from snagging.

An example of a particular design we like is the sleeping pad attachment system on the Therm-a-Rest Hyperion 32. Some people like attaching their sleeping bag to their pad to ensure they don't slide off. Most of our testers, however, find this to be unnecessary. They were thus delighted to discover that the Hyperion's attachment system is designed to be functional, but removable, allowing the user to decide if the extra weight is worth the benefits.

The straps on the underside of the Hyperion that you can use to secure it to a sleeping pad are also easy to remove if you'd rather save weight.
The straps on the underside of the Hyperion that you can use to secure it to a sleeping pad are also easy to remove if you'd rather save weight.

In contrast, the closure flap on the Sierra Designs Cloud 20 serves as an example of a design that didn't score highly. This bag has ample insulation and one of the lowest EN temperature ratings in the review (17°F). However, there is no reliable way to secure its asymmetrical, zipperless closure flap. Roll to you right, the bag opens, and chilly draft ruins your night.

There is a convenient elastic cord that keeps the Backcountry Bed's zipperless "comforter" (blue) in place  but the Cloud (red) doesn't have a similar way to secure its diagonal closure flap closed.
There is a convenient elastic cord that keeps the Backcountry Bed's zipperless "comforter" (blue) in place, but the Cloud (red) doesn't have a similar way to secure its diagonal closure flap closed.

Conclusion


Marketing claims and a huge number of options combine to make sleeping bag shopping a tough undertaking. Our extensive testing process and thorough assessments aim to crack the code to help you choose the right bag with confidence. We love the outdoors and hope this resource is one of many we can provide to improve others' experiences in nature.


Jack Cramer and Ian Nicholson