We tested backpacking sleeping bags from REI, Western Mountaineering, Nemo, Big Agnes, and more to find the coziest, most lightweight, and most packable models
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Over the last 11 years, we purchased and rigorously tested 110 of the best backpacking sleeping bags. This review covers 20 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.
Editor's Note: We updated this review on October 28, 2022, to include more information on our weighted test metrics and and to ensure that we still stand by our chosen award-winning sleeping bags.
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.
The price of a down sleeping bag seems to be creeping up 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, 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.
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 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. This bag's disappointing feature set includes a frustrating zipper and annoying hood closure. It also lacks 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 for less.
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.
We love backpacking. Our experience with over 100 throughout a decade of sleeping bag testing has lead us to keen insight. We are happy to share our top recommendations with you to help you enjoy the backcountry as much as we do.
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.
If you truly detest carrying any extra weight in the backcountry, consider the Feathered 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 twosomes who will use it regularly enough to get their money's worth. 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.
A two-person sleeping bag, like the Feathered Friends Spoonbill UL, is the absolute lightest solution for backcountry overnights.
Credit: Jack Cramer
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Backpacking sleeping bags emphasize lightweight and minimal packed size to help you sleep comfortably miles from the trailhead.
Credit: Jack Cramer
Why You Should Trust Us
Our review team researched over a hundred of the most popular backpacking sleeping bags before purchasing 20 of the best to undergo extensive hands-on testing. We measured warmth, weight, and packed size in the lab. We assessed the remaining performance characteristics, including comfort, versatility, and design, 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.
Recording our thoughts during a field test with the Feathered Friends Hummingbird.
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. 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, GearLab's policy to purchase every piece of gear that we test gives us the flexibility to include models from both makers in this comprehensive review. And we're glad we did, because they're well-made products that ended up with some of the highest overall scores.
Our testing of backpacking sleeping bags is divided across six different metrics:
Warmth ((20% of total score weighting)
Weight (20% weighting)
Comfort (20% weighting)
Packed Size (15% weighting)
Versatility (15% weighting)
Features & Design (10% weighting)
Lead author Jack Cramer is an accomplished climber, former 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.
Cowboy camping under the stars is always a treat, but be wary of rain or dew with a down-filled bag.
Credit: Jack Cramer
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.
Value
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. Anyone willing to shell out for a high-end sleeping bag should opt for a model from one of these manufacturers. Their exceptional sleeping bags, however, are beyond the budget of most people.
Many bargain sleeping bags are too heavy or bulky for backpacking. The Trailbreak 30, however, is affordable and provides acceptable performance for human-powered adventures.
Credit: Jack Cramer
For less than half the price of the 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. And because they're from REI, it's often possible to buy them at a discount.
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 translates into 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 insulation composed of synthetic fibers 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.
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.
Credit: Jack Cramer
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 32 in temperatures 10° above its 32°F rating.
Despite the introduction of EN ratings, companies still chose the temp rating they market a bag at. Marmot leaves a nice buffer between the Hyrdogen's EN lower limit rating (23.4 F) and its marketed rating (30 F).
Credit: Jack Cramer
Further complicating warmth is the fit and design of a bag. A loose-fitting sleeping bag will leave extra interior space that your body needs 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 snugly but not tight. Other design features that can 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. They're generally not necessary for a summer backpacking sleeping bag, but we like to see them on bags with 20F ratings and below. The Rab Neutrino 400 and Western Mountaineering UltraLite are two bags that feature excellent draft collars
Features like draft collars and zipper baffles can help ensure that your body heat stays trapped inside the sleeping bag, boosting the overall warmth.
Credit: Jack Cramer
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 at elevation or during the shoulder seasons.
All bags are designed to be used with a good sleeping pad to insulate you from the ground. Without one you'll be lucky to sleep at all near a sleeping bag's temperature rating.
Credit: Jack Cramer
Keep in mind that for your bag to perform up to its temperature rating, you need a quality sleeping pad and protection from the elements in the form of a good tent. It's not hard to find online complaints about bags not living up to their temp ratings. We know some folks sleep colder than others, but in some cases, we believe the culprit is an inadequate sleeping pad.
Weight
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 reduce 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 bag we tested was a 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.
The Hummingbird 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.
Credit: Jack Cramer
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 20, 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.
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.
Credit: Jack Cramer
Premium ultralight bags, like our favorite Feathered 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 lightweight choice would be the Mountain Hardwear Bishop Pass 30. At 1.79 lbs, it's not the absolute lightest bag, but the few extra ounces are easy to see past when you're spending half as much money.
The best warmth-to-weight ratios are achieved with two-person sleeping bags. Non-romantic partners might be hesitant, but the weight savings is substantial.
Credit: Drew Smith
Comfort
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.
The Sierra Designs Cloud (red) uses a zipperless flap to seal you inside. This is great for reducing claustrophobia but it doesn't stay closed as reliably as a traditional zippered system.
Credit: Jack Cramer
Three bags provide impressive comfort in three different ways that are worth discussing. The Sierra Designs Cloud 20 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-quarter-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.
The Nemo Riff 30, see here at the right, tapers far less from head to foot than an ordinary mummy bag. That leaves your legs with lots of luxurious room to stretch out.
Credit: Jack Cramer
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.
Check out the difference between budget down and ultra-premium. The 850+ FP down of the Western Mountaineering MegaLite (right) lofts 6 inches upward, while the cheaper 650 FP down of the Klymit KSB 35 (left) lays nearly flat on the ground.
Credit: Jack Cramer
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. The lightest sleepers among our testers, however, quickly noticed that particularly 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 probably avoid this fabric. Fortunately, the Hummingbird can also be purchased with much quieter—but slightly heavier—Pertex Quantum fabric.
Bags in their included stuff sacks. We love it when the manufacturer includes a compression stuff sack for the sleeping bag, adding value and reducing packed size.
Credit: Jack Cramer
Packed Size
The bigger your backpack is, the further its weight moves away from your center of gravity. This can make hiking with your backpack more strenuous, leading to premature fatigue and ultimately less fun in the outdoors. 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.
The Feathered Friends Swallow stuffed in an after-market compression sack (left) and the stuff sack that it comes with (right).
Credit: Jack Cramer
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 the two-person Spoonbill is large on its own (right), it's considerably smaller than the combined size of the two single-person bags on the left that offer similar warmth.
Credit: Jack Cramer
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 sleeping bags. Depending on your budget, however, it may be worth checking the difference in packed size between a premium and budget backpacking sleeping bag you're considering.
All down bags will lose a substantial portion of their insulative power if they get wet. Hopefully, you get a sunny day to dry them back out.
Credit: Jack Cramer
Versatility
Versatility is our assessment of how useful a piece of gear is for a variety of activities and conditions. For backpacking sleeping bags, we evaluate it by considering the usable temperature range, how well a bag performs if it gets 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, Rab Neutrino 400, 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. Many of our testers also appreciate center zippers, such as the one on the Outdoor Vitals Summit 15, for more symmetrical venting in warm conditions.
The yellow strips on the top of the Nemo Riff are called "thermo gills." A small zipper cleverly allows you to spread out insulation for shedding heat on warm nights.
Credit: Jack Cramer
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 Therm-a-Rest Hyperion 32 and Sea to Summit Spark II, can make sleeping on a warm summer night far less pleasant. Marmot has also tried to enhance venting on the Marmot Helium 15 with a secondary zipper that allows you to fold the collar back. In our tests, this design seemed rather ineffective and we would much rather see the same materials used to extend the length of the main zipper.
The Marmot Helium's main zipper to the tester's left is augmented with a short secondary zipper to his right. The idea is that the secondary zipper allows you to vent excess heat. In reality, it's so short that it hardly seemed effective.
Credit: Jack Cramer
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.
The makers of all these bags call the zippers "full-length" but there is a noticeable difference between Nemo (orange), Western Mountaineering (blue), and Feathered Friends models (red).
Credit: Jack Cramer
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.
Some bags, like the Riff 30, utilize waterproof fabric on the footbox to prevent moisture on a snow cave or tent wall from soaking in.
Credit: Jack Cramer
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.
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.
Credit: Jack Cramer
In addition, we have concerns that hydrophobic treatments may be used to inflate the fill power rating of otherwise inferior down. Some hydrophobic treatments have been shown to boost the tested fill power so a batch of 750 fill power down could potentially receive a treatment and then test at 800 fill power. When the treatment wears off after a year or two, you would be left with the original 750 fill power. Among premium sleeping bag choices our most experienced testers now actively search for models that are not hydrophobic.
Bags with truly full-length zippers, like the Feathered Friends Swallow, can be zipped open to share as a quilt on really cold mornings.
Credit: Drew Smith
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.
When it comes to stash pockets, we prefer that they're located inside rather than outside the bag. This ensures that the batteries in your electronics stay warm and holding a strong charge.
Credit: Jack Cramer
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.
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.
Credit: Jack Cramer
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 that 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.
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.
Credit: Jack Cramer
One concerning change we've noticed on several backpacking 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.
The half-length zipper only has a single slide. This greatly limits your options for venting excess heat. It could also be a huge problem if the zipper gets misaligned--there isn't any way to back it down and restart it.
Credit: Jack Cramer
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.
The pins at the bottom of most zippers (center) are necessary to get it restarted if the teeth become misaligned. Unfortunately, the Sea to Summit Spark II (left) and Thermarest Hyperion (right) both lack these important pins.
Credit: Jack Cramer
Conclusion
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 an inexpensive car-camping model. We hope this review has keyed you into the best model for your needs.
If you've been itching to hit the trails, get your paws on...
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