Sleeping bags are one of the most important components of your overnight kit. A poorly suited sleeping bag can easily make or break a good night's sleep and can turn the trip you've been dreaming about for months into one of the worst weeks of your lift. Remember, a good night's sleep will allow you to recover more effectively and perform better on the next day's hike. Sleeping bags are also unquestionably the most efficient way to keep your body warm in the backcountry; they're just so much warmer than any clothing for the weight. Thus, for the weight conscious adventurer, choosing the right bag is arguably the second best way (after a tent) to the reduce the weight of your backcountry kit.
Start by considering where and when you'll use your sleeping bag most often. You don't necessarily need to buy a bag for the coldest trip that you imagine yourself one day going on. Instead, buy a bag for the type of trip you most frequently go on and then take a few small steps to make it work for the rare colder ones. For example, for the occasional colder trip, plan to wear more layers or intentionally bringing an extra puff coat or some insulated pants. This will save you from carrying a bunch of necessary weight of a bag that is too warm most of the time as well as meaning that you won't overheat on a majority of your trips.
The first and arguably most important factor to consider when purchasing a sleeping bag is what type of insulation material is best to keep you warm through the night. Backpacking sleeping bags are available with two primary insulation types: either down or synthetic insulation. There are of course several varieties of synthetic and down insulation which we will discuss in detail lower in this article.
When choosing which type of insulation, consider the application of this sleeping bag, the environment, and the conditions in which you are traveling. Your budget and your experience level should also play a role in determining which insulation material is best for you. There are several differences between these two insulation types, but the main characteristics to focus on when deciding between the two are: synthetic materials ability to insulate when wet and dry much, much faster than down are its primary advantages. To the contrary down offers vastly superior weight savings, a smaller packed volume, better overall longevity (lasting 3-4 times as long on average) and lastly, cost; with down generally running much more expensive than synthetic models.
We choose to review far fewer synthetic bags than down bags. This is primarily because other than synthetic insulation's ability to maintain loft when wet and dry much faster, for the majority of people, it's worth it to spend a little more money and get a bag that generally performs better and will last 2+ times as long. The old mantra of "synthetic bags keep you warm, when wet" is mostly true, but it's worth noting that a soaking wet sleeping bag isn't that warm even if it's insulated with synthetic materials, and that the much bigger advantage is significantly quicker drying times.
In our side-by-side testing, we found that synthetic bags dried in roughly 20% of the amount of time as a comparably wet down bag and offered significantly better, but not perfect insulation when wet. Soaking wet bags and drying times aside, due to the trade-off of reduced longevity, heavier weight, and double the packed size, we choose to review more down bags and think for the majority of users a down bag is a better option if people are willing to spend a little more.
We'd like to remind folks that it isn't that challenging to keep a down bag dry under most circumstances, though there are no doubt exceptions. Good techniques can be as simple as utilizing a waterproof stuff sack or even just a garbage bag lining your bag's stuff sack. This will protect your bag while hiking from driving rain, snow, or rouge leaky water bottle. Once in a camp, tactics change but they still don't require that much work: remember a little condensation from the inside of your tent that migrates onto your down bag is NOT going to soak it and will have very little effect on its loft and warmth. With that said keeping your tent well ventilated to minimize condensation is still a very good idea. Tester Ian Nicholson, who guides in very damp Pacific Northwest over 70 nights a year, exclusively uses down bags. With that said, in damper areas (coast hiking, kayak camping, etc) synthetics take less effort and dry much quicker. The last reason to consider synthetic bags is if you are on a budget or don't plan to use it much, then synthetic bags can provide plenty of performance for a much more reasonable price.
Down sleeping bags have a much higher warmth-to-weight ratio, are more compressible, and last 2-3 times longer than their synthetic counterparts. On average, down bags pack down to roughly a half the size of their synthetic counterparts and weigh on average about 30-40% less. Even when taking all of that into account, our review team thinks the biggest reason to buy a down option is that a well cared for down bag (Well-cared for AKA not leaving it in a compression sack for months-on-end and drying it out after use) will last most people 20 years or even more. On the other hand, synthetic insulation will break down and lose loft over time; most synthetic bags will lose a significant amount (20-30% percent) of their warmth after just five or six years of average use.
The primary downsides to down bags are that they more expensive, and they lose significant loft when wet; meaning they won't keep very you warm if soaked or even partially wet (more than just condensation). The other disadvantage is it takes roughly fives times as long to dry out compared with a synthetic model. Of course, not all down is created equal, and all the down used in the outdoor recreation world is assigned a "fill-power," which is a quality or loft rating that affects how much insulation a given amount (by weight) of down provides. Higher quality bags (AKA higher fill-power) offer more insulation for a given weight; the result is less total weight in down insulation is required to achieve the same loft and subsequent warmth.
Water Resistant Down
A majority of the down bags we tested like the REI Co-op Igneo 25 feature hydrophobic down. Hydrophobic down is created in slightly different and often proprietary ways, depending on the manufacturer, but the process nearly always involves using a molecular-level polymer-coating that covers the individual down clusters to improved water resistance (which also makes the fibers more hydrophobic) and facilitating slightly faster drying times.
A report by the International Down and Feather Testing Laboratory noted that on average, hydrophobic down "absorbed 5.2% less weight in water, and "trapped" roughly half the weight in water as an untreated sample of the same down resulting in down clusters that dried about 30% quicker.
Some companies have claimed that they're treated down insulation "stays dry ten times longer, retains 170% more loft when exposed to moisture, and dries 33% faster than untreated down". Our only problem with those statements is they are they tend to be quite vague, and rarely specifically say what those numbers are compared against, nor do they explain how they are getting those drying times.
Our side-by-side testing can't seem to replicate results even close to as good as they claim. In our testing, both side-by-side in the "lab" as well as use in the real world, we found there was some difference, but it wasn't enormous. With light amounts of water in our spray bottle test, treated down did appear to absorb less water and dried roughly 25% faster. Slightly surprisingly, in our "full soaking-wet tests," there was even less of a difference with more similar drying times. During practical everyday use, our review team noticed very little of a difference (there were fewer opportunities for "soaking wet" comparisons) and think hydrophobic options only offered slightly better water-resistance and marginally faster drying times.
Goose Down Versus Duck Down
According to International Down and Feather Testing Laboratory (IDFL): one of the worlds foremost authorities on down and feather insulation across; geese tend to produce a better product than duck. They typically offer a more consistent and higher volume of higher overall quality down with better longevity when compared to Duck down; though this certainly doesn't mean that all goose down is better than all duck down.
There is quite a range of quality in both types of insulation, and high-quality duck down is still far superior to mediocre quality goose down. You can find high-quality 800+ fill duck down; there is just much less of it compared to goose down. This happens because down clusters from geese are generally bigger than ducks because they typically come from larger, older birds. Because goose down clusters is bigger, they can produce a larger volume of higher fill-powers on a more regular basis and offer slightly better overall longevity.
There is a big difference in the supply chains of different down manufacturers. Companies rarely raise geese or ducks strictly for their feathers; they are bred for their meat, which while rarely eaten in the United States, are regularly eaten in eastern Europe and China (and the down feathers are a by-product of this). Most reputable outdoor brands pride themselves on down that's reasonably sourced, avoiding live plucking and offering the animals a decent living environment.Ethics?
Down can be harvested in a variety of ways. Some birds are killed for their down and meat, while others are killed solely for their down. Some birds, geese, in particular, are live-plucked of their breast feathers. Others, such as the eider duck, line their nests with down, making harvest a pain-free process. Animal rights activists consider live-plucking to be a cruel and painful process, especially because it happens regularly. Some companies, such as Patagonia, do not use down from live-plucked geese or down harvested from animals that were force-fed to produce foie gras. Some of the smallest premium companies, such as Western Mountaineering, source the highest-quality down from geese that aren't live-plucked or force-fed; they collect naturally shed down from molting. Some vegans might consider avoiding down products or purchase them from a company such as Western Mountaineering, that guarantee no harm to animals.Down quality has not improved over time
Fill power ratings have increased over time as fill power testing procedures have changed. Fill power ratings represent the maximum potential performance under ideal laboratory conditions, i.e., after a one-ounce sample of down has gone through a five-day "spa retreat" of washing and drying and fluffing. Geese have not developed better ways to produce down; we've merely improved our ability to test down's potential performance under ideal conditions. The result is that fill ratings today are roughly 130 points higher than they were fifteen years ago, even though the down is the same.
Shell fabrics and water resistance
We examined each model's shell fabric and its overall performance, comparing each models water resistance, thickness, down proof-ness (where applicable), and comfort against our skin and durability.
Denier, commonly represented with a capital D, is used to determine the thickness of a given fabric by comparing the number and width of the fibers that make up a given material. This number technically refers to the weight of a specific nylon fabric, though these numbers are also used to generalize the strength and durability of given fabrics with reasonable accuracy.
While higher denier numbers generally mean greater strength, there is a grey area among fabrics that are close in denier but where quality may be a more important factor rather than 5-10D thicker fabric. For example, the Sea to Summit Spark III or the Rab Mythic 400 which uses an extremely low weight 10D and 7D fabric respectably, are both water resistant and down-proof. In theory, you could have a lesser quality 15D fabric that would be less down proof and even less strong than these fabrics, but it would be unlikely to find a 25D fabric even of low quality that you could say the same thing about.
You are probably wondering how much does fabric weight actually matter to you? Well, when just taking into account the shell fabric with no insulation factored in, the lightest 7-12D models we tested are 15 to 20 percent lighter compared with average bags using 30-50D nylon shells and 40-50% lighter than the heaviest ones.Shell Durability
Thinner fabric does mean less puncture and abrasion resistance and generally lower denier means less durability overall. However, it is important to remember that no sleeping bag we tested is extremely durable, and even the 75D, if it's being rubbed up against rocks or comes into contact with sharp objects, will tear. For example, many packs are made of 250D fabrics with 500-1000D in high wear areas. Overall we don't typically find the lower denier bags to be at a significant disadvantage because sleeping bags just don't see that much wear and tear as far as abrasions go. Most things that could cut a hole in a 12D bag would cut a 50D bag just as easily.
The most water resistant bags we tested are the Western Mountaineering UltraLite, Western Mountaineering Summerlite and the Western Mountaineering MegaLite. All three of these models use a very water-resistant shell with a solid DWR coating. Our testers were impressed at how these bags minimized the amount of condensation they would absorb from the sides of the test. That said, not these bags nor any other are even close to being waterproof; if you think there was even a chance your bag was going to get soaked, we would hope you realized that ahead of time and took the necessary precautions (or brought a synthetic bag).
Care of The Sleeping Bag
Proper care is essential for prolonging the life of your sleeping bag regardless of the insulation type. Proper care will help maintain your bag's loft and preserve its warmth and temperature ratings which will lead to longer overall longevity. In the short term, keeping down bags dry is imperative for them to function as an insulating layer during your trip. However, your down bag will eventually dry out and be just fine, and it isn't necessarily bad for it to get soaked at all from a long-term longevity standpoint, it might just be a bummer if you're forced to sleep in it in the short term.
See our Best Sleeping Bag Stuff Sacks review for suggestions regarding in-the-field storage options. Regardless of insulation type, both down and synthetic bags should be stored at home in a large, breathable storage bag where the down or synthetic insulation is not even partially compressed as this will help maintain loft FAR LONGER. Washing down bags with a very mild soap designed for washing down garments (AKA no detergent) and sleeping bags is important. Western mountaineering has a great page found here that is dedicated to the ongoing care of down sleeping bags and garments.
Synthetic sleeping bags take less maintenance in the short term. They can experience more moisture and remain warm and are generally less fragile than their lightweight down counterparts. For example, if you put a big hole in your synthetic bag, nothing will come out, unlike a down model which will need to be repaired to minimize losing feathers.
Synthetic bags are also easier and less stressful to wash, as the insulation tends not to clump when wet and can be dried easily. However, the nature of synthetic insulation fibers leads them to deteriorate more quickly than down. It is imperative to avoid compressing these bags as little as possible over time, as the more the fibers get squeezed and then allowed to expand, the faster they break down and lose their insulation qualities. For this reason, a high quality down sleeping bag is a better investment in the long run than a synthetic one as the fibers can withstand significantly more of these compressions and re-openings than synthetics. Down bags can be compressed over and over and with a few minutes to stretch, the down will return to its lofty self for years to come. However, storing them compressed in a stuff sack will eventually break down the down fibers and ruin it too. Don't worry, it's fine for the weeks you are using it every year; just don't put it in your attic for the next 7-months in a compression sack.
Don't pull the down OUT of your sleeping bag!!!
All down bags will leak some down at some point, regardless of their exterior material or craftsmanship. Certainly, higher quality bags will typically leak less over time, but some leakage is inevitable. When your bag leaks down, and there is a plump of down hanging half-out DON'T pull it out from the outside. This will actually make the hole larger and encourage more down to leak out eventually. Instead, pinch the feather plum from the inside and pull in back into the bag. This will make it less likely that more down will escape in the same spot.
Types of Construction
Three-season down bags use three major types of baffles (compartments for down).
These baffles have a seam that pierces through both fabrics; this is the lightest, coldest, and cheapest way to build a down bag.
These baffles run from the bag's head to toe, and usually, have several mesh walls to prevent the down from migrating. Vertical baffles make it easy to construct comfortable hoods and toe boxes.
These baffles create the highest warmth-to-weight ratio and are used in what we believe to be the best three-season and winter bags. Continuous horizontal baffles offer the greatest versatility for three-season conditions because they allow you to shift down from the top of the bag to the bottom of the bag for warm weather, and from the bottom to the top of the bag for cold weather. Our highest rated backpacking bags have continuous horizontal baffles.
Synthetic bags are constructed in similar ways. Some are sewn-through, others alternate the location of seams to increase warmth.
Backpacking Sleeping Bag Shapes
It has been argued that traditional style bags are overkill for many situations and come with significant pitfalls for the weight and function conscious. But they are conversely more versatile across a wider range of temperatures overall. For example, no one brings a quilt up Denali. Traditional bags adapt to different environments well and are user-friendly. Traditional style bags are a good choice for most backpackers, climbers, and car-campers. Let's discuss some of the pitfalls of the traditional bag for the uber weight conscious and function-oriented users:
Insulation works because it provides open space for warm air to collect close to your body. If it is compressed, there is no dead air space within the insulation material for the warm air. If you sleep on your back, the insulation in the bag is compressed to the point that it does not provide any more insulative quality than your sleeping pad itself. In this case, you may consider the weight of that insulation to be wasted. However, some people move in their sleep and with practice, they can move with the bag and keep themselves wrapped in insulation. If you remove insulation from the bottom of the bag, it should have a way to attach to the sleeping pad so that you can move within the bag, and thus not expose the uninsulated bottom of the bag to cold air. A quality sleeping pad is a necessary piece of your sleeping system. They provide insulation from the ground and make for a more comfortable night's sleep.
Zippers provide an easy entry and exit to and from the bag but are heavy. They require extra sewing to attach them to the bag, and the zipper weighs a bit itself . However, traditional, hooded bags are tough to get into and out of without zippers. One solution for the weight conscious is to consider lightweight bags such as the Sea to Summit Spark Sp III or Rab Mythic 400 and the Mountain Hardwear Mtn Speed 32, which both use shorter ½-¾ length zippers to save some weight. Look for bags with good draft tubes along the zipper to keep warm air in and cold air out. Keep zippers clean and treat them with care in order to keep from breaking them. We like tape-stiffened draft tubes like those on the Western Mountaineering models which provide for snag-free zipping and unzipping.
Hoods are unnecessary if it is warm out, and they can be uncomfortable. It is true that hoods can create a stuffy and hot sleeping environment during warm nights. The cords, velcro, buttons, and locks that adjust and close hoods can be a nuisance to operate and uncomfortable to lay on. We address these issues when rating the comfort of the products in our reviews. Consider a hoodless bag if you are very weight conscious, sensitive to the closeness of the fit of a hood and if you are confident that the conditions you are using the bag in are suitable for using a detachable hood or hooded clothing to provide the insulation that you need.
Applications for Traditional Bags
The best application for traditional style bags with is three-season use. They are good choices for people who need a bag that can go from car-camping to backpacking across a wide range of conditions/temperature ranges. Traditional bags are also a good choice when comfort and warmth are top priority. This may be changing with the introduction of the "Backcountry Bed" style bag from Sierra Designs.
When weight matters, our testers will use a quilt-style bag. Quilts are light and comfortable, but they require more set-up, aren't well suited for people who move a lot in their sleep, and aren't suitable when temperatures get cold.Clothing and Traditional Bag Fit
There's more innovation and variety with down bags, because down is the highest performance insulation, than with synthetic bags. Choosing the right type of fixed girth bag will come down to efficiency versus comfort. The most efficient bags will give your body just enough room to move a little, but not enough to create drafty dead air space. The most efficient sleep system involves clothing. Our testers choose their clothing and traditional bag with the intention of being just warm enough on the coldest night of a trip. And on the coldest night(s) our testers wear all of their clothes, except waterproof materials, inside of a bag.
When it comes to traditional bag comfort, wiggle room is important. The more space to sprawl about, twist and turn, and toss around-- the better! When choosing the most comfortable bag, our testers aim to be warm enough on the coldest night with minimal clothing. Unfortunately, wider bags are less efficient at keeping you warm. Your body heats up the air around you, and when you move (in a wide bag) you may open a pocket of dead space (cold, unheated air) and need to start over by heating up a new area. This is the case with larger mummy bags and all rectangular and semi-rectangular bags. Therefore, from a weight and thermal efficient standpoint, the single most crucial part of selecting a bag is fit. It is up to you to balance comfort and warmth.
Bottomless Traditional Bags
Feathered Friends Vireo is a hoodless and zipperless bag with more fill in the foot area than chest area- it's designed to be worn with a hooded jacket in colder conditions or used in alone warmer weather.
Adjustable girths are the solution to sleeping bags' greatest drawback - fit. A bag that's too large will leave cold, dead air spaces- the bag is less thermally efficient. A bag that's too tight won't be able to loft properly. Variable girths accommodate changes in clothing (in colder conditions we might wear a lightweight down or synthetic jacket). Traditional style bags are plagued by a fixed circumference that is incapable of adapting to the varying conditions typically found by backpackers. The most thermally efficient traditional bag (a trim-fitting bag) will be too slim to accommodate additional clothing in colder conditions and too slim for a broad-shouldered male friend. Quilts better fit a wider range of conditions and body types and are the best type of bag for weight conscious backpacking.
Most bags have a hood that can be drawn around your head in cold weather. Hoods are important because you lose heat through any exposed portion of your body. Your core and lower body are cozily contained in a sea of insulation in the rest of your bag, but your head can be left out in the cold without a good fitting hood. Since hoods vary in comfort, we encourage you to get inside the bag you're considering and fully tighten the hood and neck baffle. Can you still breathe? Can you turn over or change position without suffocating? Does the drawcord feel constricting or uncomfortable? Try out different bags because hood designs vary considerably.
A neck baffle (a.k.a. draft collar) is an insulated tube that prevents heat loss from around your shoulders and neck. While rectangular or ultralight bags may not have draft collars, they remain an essential component of winter bags. Neck baffles should be sufficiently voluminous to fill the void between your neck and shoulders, but not so gigantic that you feel like you're wearing a tire around your neck. Good neck baffles have elasticized drawcords that stretch when you move. The best neck baffles are asymmetrical to conform to your neck, and have differential pull cords (one round and one flat) so that you can feel what part of the bag you're tightening in the dark.
down hood for colder conditions. The obvious disadvantage of hoodless bags is they are less warm and don't offer as much versatility across temperature ranges. As a whole, we like hoodless bags for specific long-range summer trips but prefer models with hoods for nearly everything else, and certainly, anytime it is even going to be relatively cold.
Bed Style Bags
Some companies offer a lifetime warranty on material and workmanship. Others don't. Most will repair damaged bags for a reasonable fee.
Stuff and Storage Sacks
Stuff sacks and compression sacks pack your bag down for your time in the mountains or on the water. Storage sacks let the insulation loft when the bag is not in use. Of the 70+ plus bags we've reviewed, none of them include the perfect stuff sack or compression sack. Get yourself a small and light compression sack that's durable enough to withstand several hundred compressions. We have written an excellent article on selecting the best stuff sack.
Tips and Tricks
- Wrap the bottom of your bag in your hardshell or rain shell to prevent it from getting wet from condensation absorbed from the tent wall. How: close the jacket's front zipper, tuck the hood and arms inside, and slide the jacket over the foot of the bag. This prevents condensation (on the inner wall of the tent) from getting your bag wet. It's more important with down bags than synthetic, but don't do it if your jacket is wet. Keep the jacket's arms out and open the pit zips slightly if you find that the jacket isn't breathing enough.
- For cold-weather bags, get a long size. This gives you extra space for clothing, boot liners, batteries, water, and electronics.
- Dress well. Wearing excess layers in a trim-fitting bag will compress the insulation, thereby preventing it from lofting to its fullest and keeping you warm. On the contrary, adding layers will take up dead air space if the bag is too roomy.
- Keep your bag dry. Line your stuff sack with an extra thick trash bag, compress the sleeping bag, twist the garbage bag and tuck it into the stuff sack, and compress further. For multi-day trips, we also recommend lining your backpack with an extra thick trash bag and packing everything inside that. This will keep the contents of your pack dry even during large river crossings where the bottom of your backpack gets submerged.
EN Testing: Why We Don't Rely On It
The European Norm 13537 is a standardized test that measures sleeping bag warmth. The test uses a copper mannequin, fitted with 20 sensors, that wears long underwear and socks, and lies on top of a thin sleeping pad and an elevated 12mm thick wood platform. The mannequin lies inside of a sleeping bag in a temperature-controlled room while its sensors and mathematical models attempt to estimate the bag's warmth. Results from EN testing provide us with three numbers:Comfort Limit: based on a standard woman having a comfortable night's sleep
Lower Limit: the lowest temperature a standard man can sleep comfortably
Extreme Rating: a survival rating for a standard woman
The problem with standardized tests of all types is that they only measure how well a person or product does on the test, and the trial may have little to no correlation to how well that person or a product performs in real-world conditions. Thus, EN testing only measures how well a sleeping bag performs on the EN test. Is EN testing similar to real-world situations? Yes and no.
Most people sleep on their backs, the position the mannequin is in, but not everyone has the same body type as the mannequin, and the EN sleeping pad is nowhere near as warm as those used by most people today. For example, thin closed cell pads like the one used in EN testing, generally have an R-value around 1. Modern lightweight inflatable pads like the Therm-a-Rest NeoAir XLite (R-value 3.2) are 300%+ warmer. The warmer a pad is, the less insulation you need beneath you, and the less insulation, the lighter the bag. Therefore, bags with little or no insulation on the bottom have poor EN scores. Yet some of us want the lightest gear possible…
Many of OutdoorGear-Lab's highest-rated bags are not EN tested. This is because: 1) they're made by small companies that can't afford the expensive test (Marmot, for example, ships bags to a lab in Norway for testing) 2) some companies may not believe EN testing provides their customers with valuable information, and 3) a bag's design may not be compatible with the test. For example, quilts and all non-traditional bags might not have hoods or insulation on the bottom. Furthermore, factors like an individual's body type, clothing, sleeping pad warmth, type of shelter, and food and drink can all affect one's sleeping experience. And, above all, how a bag fits your body has more influence on warmth than any other bag-specific attribute.
We do not believe EN testing is the ultimate method to compare bag warmth across a wide range of bag types. Instead, we rely on our testers' assessment of warmth. Most of our backpacking gear testers have spent so much time playing and sleeping outdoors (years) that they know exactly how their body performs in various conditions and how those conditions will influence how warm they are at night. For example, after v hours of w type of exercise with x to eat and drink, y clothing, and z weather, our testers can assess a sleeping bag's warmth and compare it to previous experiences with other bags after just a few nights. For our purposes, we believe this method is better at comparing a variety of sleeping bags types than EN testing and maybe putting college kids in the meat freezer.
Though this standardized rating does allow for some comparison of warmth across brands, our advice is to approach sleeping bag temperature ratings with some degree of caution. Without significant personal experience with a particular brand or type of sleeping bag, or without significant experience with sleeping bags in general, you should be conservative. Ask questions, read our reviews and get into several sleeping bags to assess their fit and characteristics that contribute to keeping you warm. Continue to eat well and stay hydrated in the outdoors and experiment with different shelters and clothing options for the given conditions. Comparison between bags and your personal systems in a wide range of conditions is a better measurement than any standard. Hopefully, you will travel in and experience a wide range of conditions in all of your adventures. We can't all have a bag that is ideal in them all, so aim for something that will be good in most of those situations.