Over the last 11 years, we purchased and rigorously tested 107 of the best backpacking sleeping bags. Our 2021 review covers 21 of today's top models. Each bag underwent rigorous hands-on testing in the lab and backcountry, from snowy peaks in the Sierra Nevada to Death Valley's sweltering desert. Our experts considered every aspect of sleeping bag performance, including warmth, weight, comfort, and versatility. We know that you care about your sleeping bag options, and we've done our best to make selecting one an easy task. Whether you want the market's best overall bag or just a great deal, we'll lead you to the best product for your needs.Related: Best Sleeping Bags for Women of 2021
Best Backpacking Sleeping Bag of 2021
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|$459.00 at Feathered Friends||$929.00 at Feathered Friends||Check Price at Backcountry|
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|$409.00 at Feathered Friends|
|Pros||Spacious dimensions, super comfortable, great loft, lightweight, made in the USA||Super lightweight, incredible loft, snag-proof zipper, cozy hood||Unmatched warmth-to-weight ratio, respectable packed size, roomy dimensions||Best-in-class warmth, legit draft collar, light weight, exceptional loft||Best-in-class zipper, best-in-class hood, awesome loft, great warmth-to-weight ratio|
|Cons||Expensive, awkward hood, good but not great zipper||Uncomfortably narrow dimensions, bare-bones design, noisy fabric||Super expensive, limited versatility, fragile zipper||Really pricey, kind of bulky, awkward hood closure||Narrow leg dimensions, no draft collar, heavier and bulkier than some 3-season options|
|Bottom Line||The best ultra-premium bag that combines warmth, 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||The top of the line two-person sleeping bag for dedicated backcountry couples who want to really trim trail weight||Our favorite premium backpacking bag to keep us warm at night when the temperature drops||Our favorite zipper and hood in a bag that's also exceptionally warm and lofty|
|Rating Categories||Western Mountaineer...||Feathered Friends H...||Feathered Friends S...||Western Mountaineer...||Feathered Friends S...|
|Packed Size (15%)|
|Features & Design (10%)|
|Specs||Western Mountaineer...||Feathered Friends H...||Feathered Friends S...||Western Mountaineer...||Feathered Friends S...|
|Insulation||850+ FP Down||950+ FP Down||950+ FP Goose Down||850+ FP Down||900+ FP Down|
|Compressed Volume (L)||7.2 L||7.3 L||11.3 L||8.7 L||8.5 L|
|Measured Bag Weight (Size Long)||1.62 lbs||1.45 lbs||2.54 lbs (size regular)||1.86 lbs||1.94 lbs|
|Manufacturer claimed weight of size Regular (lbs)||1.5 lbs||1.33 lbs||2.63 lb||1.81 lbs||1.79 lbs|
|Compression/Stuff Sack Weight (oz)||1.6 oz||0.8 oz||1.4 oz||1.6 oz||1.0 oz|
|Manufacturer Temp Rating (F)||30 F||30 F||Not listed (20F est.)||20 F||20 F|
|EN Temp Rating (Lower Limit, F)||Not rated||Not rated||Not rated||Not rated||Not rated|
|Fill Weight (oz)||13 oz||12 oz||23 oz||17 oz||17.5 oz|
|Compression or stuff sack included?||Stuff||Stuff||Stuff sack||Stuff||Stuff|
|Shell material||Extremelite (12D)||Pertex Endurance (10D)||Pertex Endurance 10D||Extremelite (12D)||Pertex YFuse (20D)|
|Liner material||n/a||n/a||Flite 15 denier ripstop nylon||n/a||Pertex 20 denier nylon taffeta|
|Small Organization Pocket||No||No||No||No||No|
|Zipper||Full-length / Side||Full-length / Side||Dual half-length||Full-length / Side||Full-length / Side|
|Shoulder Girth (in)||64||58||105||59||60|
|Hip Girth (in)||Not stated||52||90||Not stated||56|
|Foot Girth (in)||39||38||68||38||38|
Best Overall Backpacking Sleeping Bag
Western Mountaineering MegaLite
The Western Mountaineering MegaLite is our favorite backpacking sleeping bag because it performs exceptionally in every aspect. Like other ultra-premium bags with down insulation, it offers an outstanding warmth-to-weight ratio in a bag that packs down extremely small. But unlike other ultra-premium down bags we tried, it also features spacious interior dimensions that provide superior comfort no matter your sleeping style. For virtually any overnight backcountry activity, this is an excellent choice.
Our criticisms are few and minor: the hood closure is slightly awkward, and the zipper is good but not great. A more significant issue is the steep price that is likely to dissuade a lot of shoppers. However, we believe that a high-end down bag's considerable benefits are worth the additional cost for dedicated outdoor recreationists, especially if you factor in the superior longevity of premium down. The hard choice then is deciding between the MegaLite, our favorite bag for the average backpacker, and other top-performers such as the Feathered Friends Hummingbird UL or the Western Mountaineering UltraLite.
Read review: Western Mountaineering MegaLite
Best Budget Down Sleeping Bag
Mountain Hardwear Bishop Pass 30
The price of a down sleeping bag seems to be creeping upwards in recent years. Fortunately, the Mountain Hardwear Bishop Pass 30 is bucking this trend. It's filled with a generous 15 oz of 650-fill power duck down that provides significant weight and packed size benefits. At just under 2 lbs for a size Long, this affordable bag is impressively lightweight and well-suited for any type of human-powered travel. It also showed above-average compressibility in our packed size test, and this is despite fairly spacious dimensions that never felt too cramped.
Most casual backpackers probably won't notice the drawbacks of the Bishop Pass 30. Although it is lightweight, it is not quite as light as some of the ultra-premium sleeping bags. The 650FP down insulation is also not as lofty as the higher fill power down inside its more expensive competitors. We think its 30F temp rating is pretty accurate compared to other lower limit EN ratings, but it will lose most of its insulative power if it gets wet, just like any other down bag. Despite these flaws, we believe the Bishop Pass is the best budget sleeping bag currently on the market.Read review: Mountain Hardwear Bishop Pass 30
Best Backpacking Bag for Tight Budgets
REI Co-op Trailbreak 30
Many backpackers find that paying a bit more for the performance benefits of a premium sleeping bag is worth it. However, for folks unable to financially swing that — or for those just dipping their toes into the world of human-powered travel — the REI Co-op Trailbreak 30 is worth a look. Though it doesn't live up to the performance of our favorite sleeping bags, it still performs well, and at a significantly lower price. It's definitely heavier and doesn't pack down as small as the premium bags, but we still think the Trailbreak's specs meet the threshold to be acceptable for backpacking, especially if you only make a couple trips per year. One perk is that the synthetic fill of this bag is will maintain insulation properties when wet, which the down-filled competition cannot match.
To enjoy the potential savings of the Trailbreak 30, you will have to accept some drawbacks. First among these drawbacks is a disappointing feature set that includes a frustrating zipper and annoying hood closure. This bag also doesn't include an effective compression sack (or a storage sack, for that matter), so be sure to factor the cost of those items into your purchasing decision. Nevertheless, if you're desperate to go backpacking and unwilling to fork over the dough for a better performer, the Trailbreak 30 can get you out on the trails and savoring the great outdoors.
Read review: REI Co-op Trailbreak 30
Best Bargain for a Two-Person Model
Big Agnes Sentinel 30 Double
Adventure couples on a budget will want to look hard at the Big Agnes Sentinel 30 Double. Before doing the math, this model is heavy, takes up considerable pack space, and costs significant coin. However, once the weight, packed size, and price are divided by two, it becomes evident how much space, weight, and money are actually saved with this model when split between two people. There are many double bags available on the market, but few actually meet the size and weight requirements for backpacking. This model does this impressively well while potentially also saving you some cash for a more lightweight tent or a nice sleeping pad.
Despite the added warmth from a partner, this bag didn't live up to the warmth we expected from it. This is likely due to a poor hood closure and a lackluster neck baffle, neither of which do a great job sealing in heat. And, even if you frequently backpack with your significant other, there might be times when you don't, at which point you'll also need a single-person sleeping bag in your arsenal. Still, at this price, it might be possible to build an arsenal instead of being limited to a single sleeping bag option. This model is obviously not for everyone, but couples looking to snuggle up in the backcountry on the cheap won't find a better option.
Read review: Big Agnes Sentinel 30 Double
Best for Fast and Light Adventures
Feathered Friends Hummingbird UL 30
When saving weight is paramount, our favorite bag is the Hummingbird UL. Feathered Friends uses the highest fill power down we've tried (950+) to create a bag that is extraordinarily 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 flexibility to share it as a quilt with a partner during a full-on bivouac.
It's worth noting that the Hummingbird UL achieves its low weight with notably narrow dimensions that many will find constrictive. Its ultra-high fill power down also comes with an ultra-high list price. If you can look past these faults, you get a traditional mummy bag that supplies an unparalleled warmth-to-weight ratio. There may be no better choice when the ounces really matter.
Read review: Feathered Friends Hummingbird UL 30
Best for Colder 3-Season Conditions
Western Mountaineering UltraLite
If you know you "sleep cold" or have plans for colder trips in the spring or fall, the Western Mountaineering UltraLite is the bag for you. With 17 ounces of 850+ fill power down and a legit draft collar, we have no trouble calling the warmest bag in the review. At the same time, its full-length zipper and horizontal baffle construction provide ample options to shed heat and cool off on warmer nights. In the field, we slept comfortably in this bag across an expansive range of overnight temperatures from 10° to 55°F.
The primary drawback to this exceptional performance is a staggering price tag, although many may appreciate that Western Mountaineering is a small company that produces all its bags in the USA. We also think most 3-season hikers can make do with a less insulated bag boasting a lighter weight and smaller packed size. Nevertheless, if you're looking for a fantastic bag that's almost guaranteed to keep you toasty, the UltraLite is our favorite model.
Read review: Western Mountaineering UltraLite
Best Two-Person Backpacking Sleeping Bag
Feathered Friends Spoonbill UL
If you truly detest carrying any extra weight in the backcountry, consider the Feather Friends Spoonbill UL. This double sleeping bag offers the best warmth-to-weight ratio of any two-person sleeping system that we've seen. Its 950+FP goose down supplies exceptional warmth that's comparable to that of most single bags with a 20F temp rating. At the same time, the entire double bag weighs only 2.54 lbs. That equates to nearly a pound less weight than you could manage with top-of-the-line single-person bags that provide similar warmth. The Spoonbill also offers roomier dimensions than a traditional mummy bag. Its name is rather misleading--spooning inside this bag is entirely unnecessary, but also there if you want it.
The disadvantages of the Spoonbill are mostly the same disadvantages of any double sleeping bag. The nature of the design necessitates two willing sleeping partners, which can be tricky depending on your plans, gear, and group size. The bottom of this bag is also uninsulated, so staying warm requires two good sleeping pads. It's an extremely expensive sleeping bag, so it's only ideal for serious travelers. Finally, the ends of the dual zippers are sewn directly into the bag. This creates a durability problem because if the zipper teeth become misaligned, there is no easy way to fix it. Nevertheless, the Spoonbill is just too amazingly light for the drawbacks to dissuade our testers from fighting over this marvel of a sleeping bag.Read review: Feathered Friends Spoonbill UL
Why You Should Trust Us
Lead author Jack Cramer is an accomplished climber, member of the Yosemite Search and Rescue team, 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 ideal gear for backpacking, climbing, and ski trips. They've both spent the better part of the last decade in the backcountry developing the expertise to evaluate all sorts of outdoor gear. For this review, they consulted with Appalachian and Pacific Crest Trail thru-hikers, National Outdoor Leadership School alumni, manufacturer reps, and novice backpacker friends to ensure a diverse array of perspectives.
Our review team researched more than 100 of the most popular backpacking sleeping bags before purchasing 22 of the best to undergo extensive hands-on testing. We measured warmth, weight, and packed size in the lab. The remaining performance characteristics, including comfort, versatility, and design, were assessed in the spectacular landscapes of California's Sierra Nevada, Wyoming's Wind River Range, Grand Staircase Escalante National Monument, and Death Valley National Park. Bags were tested at elevations ranging from 150 feet below to 14,000 feet above sea level with nighttime lows between 10°F and 70°F.
This review is also unique because it includes direct comparisons between Western Mountaineering and Feathered Friends products. These small, specialty manufacturers source some of the best goose down on the market, but their reluctance to give away free samples limits how many of their bags eventually get reviewed. Fortunately, OutdoorGearLab's policy to purchase every piece of gear that we review gives us the flexibility to include models from both makers in this comprehensive review. And we're glad we did because they ended up with some of the highest overall scores.
Related: How We Tested Backpacking Sleeping Bags
Analysis and Test Results
Designing anything is a balancing act, and that's undoubtedly true for backpacking sleeping bags. Add insulation to make it warmer, and a bag can quickly grow too heavy. Cut that weight by shortening the zipper, and you reduce the ability to vent excess heat. It's a game of tradeoffs that varies by personal preference and planned usage. To evaluate today's top sleeping bags, we selected six performance areas that are usually at odds with one another: warmth, weight, comfort, packed size, versatility, and features & design. We hope that the result is a comprehensive analysis that accounts for every aspect of performance, so you can hone in on the ones that matter to you most.
Related: Buying Advice for Backpacking Sleeping Bags
Price is a huge part of any purchasing decision. Sleeping bags come in a surprisingly broad range of prices for products that ostensibly serve the same purpose. After extensive testing, we can confidently say that price does seem to reflect meaningful performance differences. Nothing came close to the Feathered Friends and Western Mountaineering bags in terms of absolute performance — they demonstrated clear superiority in overall design, build quality, and warmth-to-weight ratios. These expensive bags, however, would require most people to save up to afford them.
For less than half the price of these premium bags, the Mountain Hardwear Bishop Pass 30 and REI Trailbreak 30 provide exceptional deals. Although they're a little heavier and bulkier on the trail, you will likely sleep just as well once you get them to camp. The REI Co-op Magma 15 and Magma 30 are two other bargains worth mentioning. They're not exactly inexpensive, but they offer reasonable savings over the ultra-premium models while approaching their high performance. Because they're from REI, it's also generally possible to buy them at a discount. Lastly, if you and your partner are looking for bags together, consider the value of a backpacking double sleeping bag. By sharing packed gear, the Big Agnes Sentinel 30 Double is one of the most affordable ways to decrease pack weight between two people.
Related: Best Budget Backpacking Sleeping Bag of 2021
Sleeping bag warmth depends primarily on the quality and quantity of the insulation. For bags filled with down insulation, you can make a rough estimate of the warmth by considering the fill power and fill weight. Fill power is a measurement of the "loftiness" of the down fill, and it corresponds to the amount of air a certain weight of down can trap. More trapped air means more trapped body heat. Sleeping bags usually contain down with a fill power between 500 and 900, with higher numbers indicating higher insulation ability. Fill weight is simply the amount of down inside the sleeping bag. Due to other design choices, two different sleeping bags with the same fill weight and fill power might not provide identical warmth, but they should be pretty close.
Estimating warmth is trickier with synthetic insulation because the wide array of proprietary fibers is overwhelming, and it makes a comparison between manufacturers close to impossible. However, the fill weight should still provide a rough indication--a bag with 12 oz of synthetic insulation should be warmer than a bag with 8 oz.
In an attempt to standardize sleeping bag warmth measurement, the European Committee for Standardization developed the EN 13537 standard, which is a test designed to provide consistent temperature ratings for all sleeping bags. These EN ratings seem to be more accurate than the manufacturer-advertised temperature ratings of the past, but some of the best companies still don't get their bags tested due to substantial testing costs. Also, the testing protocols' peculiar details may arbitrarily favor certain designs while offering limited information on warmth under real-world conditions.
Due to these issues, we chose to evaluate warmth using real human testers. Each bag was slept in for at least three nights in a 48°F room. Each bag's performance was assessed relative to the other bags in the review and their EN rating (if they had one). The difference between the warmest and coldest bags is 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 a Therm-a-Rest Hyperion in temperatures 10° above its 32°F rating.
Further complicating warmth is the fit and design of a bag. A loose-fitting sleeping bag will leave extra interior space for your body to heat. On a cold night, this can make you feel colder. A bag that fits too tight, in contrast, can result in your body pressing against the insulation, compressing the loft, and reducing the insulation's ability to trap heat. For maximum warmth, it's best to size your bag so that it fits snug but not tight. Other design features that can also affect warmth are zipper baffles and draft collars. Both features are additional pieces of insulation that are positioned to stop heat from escaping out the zipper and hood, respectively. You can find both on the Feathered Friends Spoonbill. This ultralight bag boasts an exceptional warmth-to-weight ratio because its two-person design causes the occupants to passively share their body heat inside its spacious interior.
Our warmth ratings are scaled so that a score of ten indicates a bag with the highest level of warmth, and a score of one indicates the least. Importantly, this doesn't mean that a bag with a ten would be the best bag for you. More likely, if you're looking for a bag for moderate 3-season conditions, a score of 7 or 8 will probably be sufficient. For most people, the bags with the highest warmth rating are best-suited for frosty nights during the shoulder seasons.
Related: Best Backpacking Sleeping Pad of 2021
Related: Best Backpacking Tent of 2021
Although warmth is hard to measure, it's easy to measure weight, and this is one of the most important metrics to consider when human-powered travel is involved. 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 they come with correspondingly high prices. Switching to a shorter zipper or a trimmer fit is a potential way to trim weight, but it will likely harm versatility or comfort. We tested and measured all the single-person bags in this review in size Long to fit our lead tester. The two-person sleeping bags were tested in size Regular.
To evaluate the weight, we used a digital scale to weigh each bag by itself, without any included stuff or compression sacks. Although we report the weight of stuff sacks individually, the 'Weight' performance category is based solely on the weight of the bag. This is under the assumption that most users will opt for an aftermarket compression sack that is more effective at compression and potentially also more lightweight. Also, keep in mind that the weight scores for the two-person bags reflect the weight of the entire bag. To fully appreciate the weight savings of a double bag like the Feathered Friends Spoonbill UL, divide its total weight by two, and you'll see that it offers 20F warmth for just 1.27 lbs per person. For the Big Agnes Sentinel Double, that's 1.6 pounds per person.
There is a 2+ pound difference between the lightest and heaviest bags in this review: the Therm-a-Rest Hyperion 32 and the Nemo Forte, respectively. This difference may not sound like much, and in the grand scheme, it may not be. In a comparative sense, however, the Forte is 214% heavier. That's enormous. If you select similarly heavy gear for your entire overnight kit, the weight difference will quickly grow to double-digit pounds. That could easily be the difference between making it to camp before dark or turning back before your knees and back give out.
Premium ultralight bags, like our favorite Feather Friends Hummingbird UL, can thus serve as one piece in the puzzle that is cutting 10-15 pounds from your load. Accomplishing this is expensive but can pay dividends for your back/knee health and overall enjoyment in the outdoors. A more affordable choice might be the Mountain Hardwear Bishop Pass 30. At 1.79 lbs, it's not the absolute lightest bag, but the weight savings are minimal unless you're willing to speed nearly twice as much.
To sleep well, you have to be comfortable. For most people, this is a simple task in a bed with a blanket and thermostat nearby. The task can be a lot 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 environment to be disruptive. The former group can ignore our comfort evaluations. The latter should devote special attention.
To evaluate comfort, we considered several factors: the dimensions and fit of a bag, the loft or fluffiness of the insulation, the feel of the interior fabric, and in some cases, the noisiness of the materials. Although being too warm or cold can affect how comfortable you are, we assess the likelihood of that happening with our separate warmth and versatility metrics. Thus, a bag's comfort score is our best subjective judgment of its performance in terms of fit, loft, feel, and noisiness.
Three bags provide impressive comfort in three different ways that are worth discussing. The Sierra Designs Cloud achieves its comfort with perhaps the most interesting approach. It's a completely zipperless bag that utilizes an overlapping diagonal flap to close. This flap supplies more freedom and less claustrophobia than a zippered closure. However, its zipperless closure is less secure, so it can feel a bit drafty. You can avoid this issue with the similarly comfortable Nemo Riff 30. It features a three-quarters-length zipper like a classic mummy bag, but it's shaped like a broad hourglass rather than a tapered sarcophagus. The bottom of this hourglass offers an extra 12 inches of girth compared to ordinary bags, which gives side and tummy sleepers ample room to stretch their legs in any direction.
While we enjoyed the Riff's innovative shape, its down insulation is not particularly lofty, nor is its fabric exceptionally soft. The final standout in the comfort department, the Western Mountaineering MegaLite, addresses these deficiencies. Its 850+ fill power down and 12-denier ExtremeLite fabric combine to create a cozy cocoon of luxurious loft. Although it's among the most spacious models in the torso dimensions, it has a classic mummy shape and narrow footbox that won't be appreciated by all.
As these examples illustrate, a bag's comfort is inherently subjective, so it's essential to choose one that matches your preferences. Those who don't detest the shape of a mummy bag 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 has always made you feel uneasy, the Cloud could be your salvation.
One aspect of comfort we failed to anticipate before testing was the noisiness of the fabric. Our testers that are the lightest sleepers, however, quickly noticed that some crinkly fabrics could disturb their sleep. This issue was most noticeable with the Pertex Endurance fabric of the Feathered Friends Hummingbird UL. Anyone concerned about noise should consider avoiding this fabric. Fortunately for the Hummingbird, it can also be ordered with Pertex Quantum fabric that is much quieter, but slightly heavier.
The bigger your backpack is, the further away its weight will be from your center of gravity. This can make it more strenuous to carry, causing you to get more fatigued and ultimately making your time in the outdoors less fun. Sleeping bags usually occupy a significant portion of an overnight backpack. Therefore, getting a bag that compresses smaller is a good way to reduce the size and burden of your overall load.
All the bags we tested include a stuff or compression sack for storing them inside your backpack. Many of these sacks, however, are ineffective at compressing a sleeping bag fully. Therefore, to evaluate packed size fairly, we used the same 11-liter Granite Gear compression sack to measure each bag's minimum compressed volume.
By and large, the compressed volumes we observed corresponded closely with the weight of each bag. A couple of exceptions are the Mountain Hardwear Bishop Pass 30, which compresses roughly 10% smaller than its weight would suggest, and the Western Mountaineering UltraLite, which packs down 15% larger than comparable bags.
Although these discrepancies are worth noting, we consider all the bags included in this review small, especially compared to Budget Backpacking Sleeping Bags or the behemoths of yesteryear. Therefore, we don't think packed size should be a crucial characteristic to distinguish between today's nicest backpacking sleeping bags. Depending on your budget, however, it may be worth checking whether the bag you're thinking of buying includes a functional compression sack. If not, a quality aftermarket compression sack is a relatively inexpensive option.
Versatility is our assessment of how useful a piece of gear is for a variety of activities and conditions. For sleeping bags, we evaluated it by considering the usable temperature range, how well they perform if they get wet, and whether a bag can do things besides keeping a single person warm when sleeping.
How comfortable a bag stays across a range of temperatures is influenced by its ability to insulate when it's cold and shed excess heat when it's hot out. Draft collars and snug hoods, such as those found on the Western Mountaineering UltraLite and REI Co-op Magma 30, are both features that can boost a bag's cold-weather performance. Conversely, a long main zipper and accessory vents make the Nemo Riff 30 ideal for warmer nights.
Overall, the bags with three-quarter or full-length zippers seem to supply adequate venting options for most 3-season conditions. Shorter half-length zippers, in contrast, such as those of the Rab Mythic 400, Therm-a-Rest Hyperion 32, and Sea to Summit Spark II, can make sleeping on a warm summer night far less pleasant.
How well a bag performs when wet is primarily determined by the type of insulation. Down feathers are notorious for clumping when they get wet, which severely reduces their ability to insulate. Synthetic fibers, in contrast, do not clump and can continue to supply up to 50% of their usual warmth even when soaked.For this reason, synthetic bags, like REI Trailbreak, are safer choices for particularly wet activities or environments. Some bags feature waterproof exterior fabric to try to prevent the insulation from getting wet at all. These fabrics, however, add considerable weight and bulk and increase the potential to trap your body moisture inside. For these reasons, "waterproof" sleeping bags never became very popular, and we have chosen to leave them out of this review.
A buzzword used to market many down bags is hydrophobic, which simply means that the down received a chemical treatment in an effort to make it more water-resistant. In our opinion, claims about the benefits of these treatments seem to be overstated. In our testing, we observed little difference between down that was treated or untreated, so we did not factor it into our versatility score. Interestingly, both top-performing bag makers, Western Mountaineering and Feathered Friends, do not use hydrophobic down. Instead, they express concern about the longevity of hydrophobic treatments and the possible harm it could do to the water-resistant oils that high-quality down naturally contains.
The final aspect of versatility that we considered is how well a bag functions in non-standard ways. We noticed that bags with truly full-length zippers, like the Feathered Friends Swallow 20 YF or Hummingbird UL, can be shared as a quilt when completely unzipped. This is a nice bonus when eating breakfast on a cold morning or while trying to survive an unplanned bivouac. The Sierra Designs Cloud, in contrast, lacks a zipper or insulation on the underside of the bag. This means that it cannot be shared easily, and it must be used in conjunction with a good sleeping pad. For this reason, it's probably not a great choice for hammock sleeping.
Features and Design
"Features and Design" is a catch-all category that encompasses the performance characteristics that are not addressed with our other evaluation criteria. "Features" include 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. This ensures that the bag's insulation doesn't get saturated from brushing against condensation on a tent wall. We're also big fans of the full-length zippers on the Feathered Friends bags. Not only do they feature a Y-shaped, anti-snag zipper slide, but there is an internal strip of plastic in the adjacent fabric to direct the fabric away from the zipper teeth and further reduce the chance of snagging.
Another example of a 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, so they don't have to worry about sliding off their pad in the middle of the night. Most of our testers, however, think this is pretty unnecessary. We are thus delighted to see that the Hyperion's attachment system is designed to be functional yet removable, leaving the decision up to you whether the extra weight is worth the benefits. We've tested plenty of other sleeping pad attachment systems that don't offer a similar degree of adjustability. Not all attachment systems are equal.
Another flaw we've noticed on several sleeping bags is a main zipper with a fixed closure at both ends. Most sleeping bag zippers include a pair of the interlocking pins on one end that allow you to connect and disconnect the left and right sides of the zipper. Although they're easy to overlook, these tiny pins are necessary for restarting a zipper if it gets misaligned. For some inexplicable reason, a few manufacturers have done away with the pins, choosing instead to sew the ends of the zipper directly into the bags.
This design creates a huge durability problem. Even if you're incredibly careful, a zipper will occasionally snag. When that happens, there is always a chance that the teeth will get misaligned, or the zipper slide will pop off from one side. With most bags, it's not a problem; restart the slide at the pins, and it's fixed. But if misalignment occurs in the backcountry with the Sea to Summit Spark II, Feathered Friends Spoonbill UL, or Therm-a-Rest Hyperion, prepare to shiver because you won't be able to restart the zipper or close the bag properly. Furthermore, fixing a misaligned zipper will likely require cutting it off the bag, realigning the teeth, and sewing it back together.
Deceptive marketing claims, a huge number of models, and preposterous prices combine to make sleeping bag shopping a daunting task. Our extensive testing process and thorough assessments aim to crack the code for three-season backpacking sleeping bags. Depending on your activities, you might be happier in a specialty ultralight option or inexpensive car-camping model. We hope this review has keyed you into the best model for your needs.
— Jack Cramer and Ian Nicholson