Sleeping bags are one of the most critical components of your overnight kit. A poorly suited sleeping bag can quickly spoil a good night's sleep and turn your dream trip into one of the worst weeks of your life. Remember, proper sleep helps your body recover and ensures you can enjoy the next day's hike. Sleeping bags are also the most efficient way to keep your body warm—much higher warmth than clothing for the weight. Thus, for the weight conscious adventurer, choosing the right bag is arguably one of the best ways to reduce the weight of your complete backcountry kit.
Start by thinking about where and when you'll most often use your sleeping bag. You don't necessarily need to buy a bag for the coldest trip you might someday go on. Instead, buy a bag for the types of overnights you do most frequently. When the rare cold trip does arise, there are several steps you can take to make a less than ideal bag work. For example, extra clothing layers, a thicker sleeping pad, or a well-sealed bottle filled with boiling water can boost your warmth in any sleeping system. These strategies will save you from carrying an unnecessarily heavy bag that is too warm for most of your trips.
The first and arguably most important factor to consider when purchasing a sleeping bag is the type of insulation. Backpacking sleeping bags are available with two primary types of insulation: down feathers or synthetic fibers. There are, of course, several varieties of down and synthetic which we will discuss lower in this article.
When choosing the type of insulation, consider the environment and conditions your bag will be used along with your budget and experience level. Generally, down bags perform better in dry locations because they weigh less and pack smaller than synthetic bags of equivalent warmth. When down feathers get wet, however, they clump and lose their ability to insulate more than synthetic fibers. For this reason, we recommend synthetics for wet climates or inexperienced users less adept at keeping their sleeping bag dry. Another critical factor is price. Down can cost several times more than a comparable synthetic option. This drawback is somewhat negated, however, by the longevity of down which can maintain its loft better after repeated packing and unpacking.
In the current backpacking product landscape, down is king. Despite advances in synthetic materials, down maintains a much higher warmth-to-weight ratio, better compressibility, and the potential to last 2-3 times long that its synthetic counterparts. In our tests, down weighed roughly 30% less and packed 15% smaller than synthetics of the same warmth. Even with these advantages, our review team thinks the biggest reason to buy down is the durability of the feathers. When cared for properly—stored dry, clean, and uncompressed—down bags can last an average backpacker up to 20 years. Synthetic bags, in contrast, can lose 20-30% of their warmth in five years of normal use.
The primary downside to down is that it is more expensive and loses significant loft when wet, which means a down bag can lose its ability to keep you warm if it's soaked or even partially wet. Another disadvantage is that after getting wet, down takes roughly fives times longer to dry than synthetic fibers. Despite these disadvantages, down is still widely considered to be superior to synthetics for most backpacking applications. For this reason—and because it was difficult for us to identify very many popular, premium synthetic options—we chose to review more down bags.
The limited number of synthetic bags we chose to include in the backpacking review, demonstrated a better ability to maintain loft when wet and dried much faster than their down counterparts. The old mantra of "synthetic bags keep you warm, when wet" remains mostly true, but it's worth recognizing that a soaking wet sleeping bag still loses significant warmth even if it's filled with synthetic fibers.
The much more significant advantage to synthetics is their significantly quicker drying times. In our side-by-side testing, synthetic bags dried in roughly 20% the time of a comparable wet down bag. Soaking wet bags and drying times aside, due to the disadvantages of synthetics in weight, packed size, and longevity, our review team believes down bags are the better option for most overnight travelers if they are willing to spend the extra money.
We want to remind folks that keeping a down bag dry shouldn't be that challenging under most circumstances. Good strategies can be as simple as purchasing a waterproof stuff sack or lining your bag's current stuff sack with a plastic trash bag. This simple step will protect your bag while hiking through driving rain or the rouge leaky water bottle. Once in a camp, keep your tent well ventilated and use a small piece of sponge to wipe off any surface condensation. Tester Ian Nicholson, who guides in the notoriously damp Pacific Northwest, exclusively uses down bags. With that said, for particularly wet
activities (coastal hiking, kayak camping, etc.) synthetics can improve your safety margin and will dry much quicker.
After choosing an insulation type, the next big decision for a sleeping bag shopper is the temperature rating. For this review, we aimed to select the best backpacking sleeping bags for use in spring, summer, and fall. Based on experience, this translated into bags with manufacturer temperature ratings between 20 and 35°F. Depending on your location, planned activities, and personal metabolism ("hot" vs. "cold sleeper"), you will likely want to choose a bag within this range for 3-season use.
The difference, however, between the warmth bags provide at the lower and upper end of this temperature range is much larger than the 15°F difference would suggest. The biggest reason for this are inconsistencies in how manufacturers assign their temperature ratings. To resolve this issue manufacturers have begun to test their bags according to the European Norm 13537—a standardized test designed to measure sleeping bag warmth.
The test uses a copper mannequin, lying on top of a thin sleeping pad, and fitted with long underwear, socks, and 20 sensors. The mannequin lies inside 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
In general, we find these numbers useful for comparing bags to one another to assess relative warmth. EN temperature ratings, however, don't seem to be as helpful in picking a bag based on the temperature forecast. Your actual comfort on a particular night will also be influenced by your shelter, sleeping pad, exertion level, nutrition, etc. For this reason, bringing a 20° bag for a 20° night will often result in discomfort. Instead, choose the EN temperature rating for your new bag based on the EN temperature rating of your old bag or other bags you've used.
In the absence of previous experience, we recommend bags at the upper end of the range (30-35°) for 3-season use at lower elevations or summer use at higher elevations. Bags at the lower end of the spectrum (20-25°) are better suited for cold sleepers and high altitude in the shoulder seasons.
An additional issue is that many of OutdoorGearLab's highest-scoring bags are not EN tested. This fact could be because they're made by small companies that can't afford the expensive EN test or a bag's design may not be compatible with the testing procedures. For example, quilts and many non-traditional bags are incompatible with EN test standards. In our testing, the manufacturer temperature rating of the ultra-premium Feathered Friends and Western Mountaineering bags performed roughly 5° better than advertised (e.g., The Feathered Friends Merlin 30° performed similarly to other bags with an EN Lower Limit of 25°)
Backpacking Sleeping Bag Shapes
Traditional style bags have been rightly criticized in some situations and come with significant pitfalls for the weight and function conscious. But they are conversely more versatile across a broader range of temperatures overall. Traditional bags also adapt to different environments easily and are user-friendly. They are, thus, a good choice for most backcountry travelers.
One of the primary drawbacks to traditional bags is the added weight of compressed insulation beneath the body that does little to increase warmth. Insulation works by trapping warm air in the tiny dead air spaces between feathers/fibers close to your body. When compressed, there is no room for dead air spaces to form to trap warm air. Whether you sleep on your side, back, or stomach, the material beneath your body compresses to the point that it is unable to provide significant insulation. In this case, many would consider the weight of that insulation to not contribute to your warmth.
Another disadvantage is the zipper traditionally used to open and close mummy bags. Although zippers enable simple entry and exit, they add weight. Extra sewing is needed to attach them to the bag, the zipper itself weighs a bit, and an additional draft tube is needed to ensure that much warmth does not escape through the zipper's teeth. Some models deal with this issue by reducing the length of the zipper from full to 3/4- or 1/2-length. This reduction can improve the bag's warmth-to-weight ratio, but it reduces your ability to vent excess heat on warm nights. Sierra Designs has tried to solve the zipper problem in a different way: by removing zippers entirely. Instead, their bags feature a large opening on top for entry/exit that seals with a blanket-like flap of fabric. This solution saves weight and improves comfort but with the cost of lower thermal efficiency.
The other problem sleeping bag zippers often create is frustrating snags. This
may sound minor, but it can be challenging to escape a sleeping bag when your whole body is inside, and the zipper decides to snag. Fortunately, many sleeping bag makers are now dealing with this issue by using new Y-shaped, anti-snag zippers. Western Mountaineering and Feathered Friends also incorporate internal stiffening tape in their draft tubes that prevents snags pretty well. Nevertheless, zipper snags remain a problem on some of the ultralight bags that employ tiny zippers, like the Marmot Phase 20 and Rab Mythic 400.Other Bag Types
Despite the disadvantage of traditional style bags, we consider them the best choice for most three-season applications. They are a popular and reliable option for anyone hoping for a good night's sleep across a wide range of conditions and temperature ranges. For these reasons, our backpacking sleeping review only considers traditional bags. However, for ultralight backpacking or other specialty applications, non-traditional sleeping bags may be more appropriate. Check out our Ultralight Sleeping Bag Review for a better look at quilts, hood-less, and back-less sleeping systems.Traditional Sleeping Bag Fit
Choosing the right fit of a sleeping bag is a balance between thermal efficiency and comfort. The most thermally efficient bags will fit snugly around your body to seal out drafts and leave little additional air space inside the bag that your body needs to heat. An overly snug fit, however, can be very uncomfortable and is one reason restless and side sleepers often complain about traditional bags. Also, when a bag is too small, your body will press against the insulation, compressing the loft, and creating cold spots.
Some mummy bags are now sewn wider to give additional room to roll around, to solve these issues. Another solution has been to change the shape of bags from the classic sarcophagus shape to more of a broad hourglass. Nemo has done this well in the Nemo Riff 30 which we recommend for shoppers who find traditional mummy bags uncomfortable. Regardless of the manufacturer, be sure to choose a bag that is the correct length, which will ensure that your head and feet won't compress the bag's insulation and compromise your warmth.
Three-season down bags use three major types of baffles to ensure insulation does not shift within the bag to create unwanted cold spots.
These baffles have a seam that pierces through both fabrics; this is the lightest, coldest, and cheapest way to build a sleeping bag.
These baffles run from the bag's head to toe, and usually, have several mesh walls to prevent the insulation 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 part of what we believe to be the best three-season and winter bags. In down bags, continuous horizontal baffles offer the most exceptional versatility for three-season conditions because they allow you to shift feathers 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 used continuous horizontal baffles.
A neck baffle (a.k.a. draft collar) is a tube of insulation near the hood opening of a bag that prevents heat loss from the main body of a sleeping bag. Although neck baffles generally have an internal elastic cord that can be cinched to ensure a snug fit around your neck and shoulders, some models are now using extended pieces of fabric you tuck beneath your shoulders to keep the baffle in place.
Neck baffles are essential for cold winter applications, but their inclusion on three-season bags is less than universal. Deciding whether to get a bag with a neck baffle in the 20-35° temperature range often comes down to personal preference. However, our testers think they increase the available temperature range while adding minimal weight.
It's easy to confuse draft tubes with draft collars (a.k.a. neck baffles). Draft tubes, however, are tubes of insulation that prevent heat loss through the closed zipper of a bag. These are especially important with center zip bags where the placement of the zipper above the body increases the potential for warmed air to rise and escape. Fortunately, most of the backpacking bags in this review have capable draft tubes. However, the absence of a draft tube can be a real problem for some budget and car-camping sleeping bags.
Shell fabric quality is typically reported with denier. Denier, commonly represented by a capital 'D,' is a measurement of the linear density of fiber. A single strand of silk, for example, is one denier (1D) and it goes up from there for most sleeping bag shell fabrics. Denier is a rough way to evaluate the strength and durability of a fabric.
Although higher denier numbers generally mean higher strength, it is a somewhat imprecise measure because denier is a measure of the individual fibers while fabric strength is also influenced by how the strands weave together. For example, the Marmot Phase 20 and the Rab Mythic 400 both use lightweight 10D and 7D ripstop nylon fabric, respectively, that performed well in our tests for durability and down proof-ness. In theory, you could have poorly woven 15D nylon that would be less down proof and weaker than these fabrics. However, you're unlikely to find a 25D sleeping bag fabric about which you could say the same thing.
Even though lower denier usually means less puncture and abrasion resistance, it is essential to remember that no sleeping bag we tested is extremely durable. Even the bag with the highest denier material, the Mountain Hardwear Lamina (30D), will tear if it's being rubbed up against rocks or comes into contact with sharp objects. In contrast, equipment designed for abrasion, such as backpacks, are typically made from 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 don't see that much wear and tear as far as abrasions go. Most things that could cut a hole in a 10D bag would cut a 30D bag just as quickly.
The Details of Down
Fill Power and Fill Weight
Not all down is created equal. To quantify the differences, down used in the outdoor recreation world is assigned a fill power (often abbreviated "FP"), which is a quality or loft rating that indicates how much insulation a given amount of down provides. Higher fill power indicates more insulation for a given weight; resulting in a higher overall warmth-to-weight ratio. This benefit, however, comes with a hefty price tag. Premium 900+ FP bags often cost several hundred dollars more than budget 600 FP bags.
Fill power can also help explain the difference between goose and duck down. According to International Down and Feather Testing Laboratory, geese more consistently produce a higher volume of higher quality down with better longevity than ducks. This fact doesn't mean, however, that all goose down is better than all duck down. Ducks are still capable of producing high-quality 800+ FP down; they produce less of it.
What does all this mean for the sleeping bag shopper? Insulation with identical fill power, whether it's from a goose or duck, should provide similar loft and warmth. Goose down, however, is generally composed of larger feather clusters that may off slightly better longevity.
In addition to fill power, fill weight has an important impact on a sleeping bag's warmth. Fill weight is simply the physical weight of down in a bag. All things equal, more down in a bag will make it warmer. Keep in mind though that the cut and design of a bag can also influence how well it seals in air and keeps you warm. In the absence of precise ways to measure that design, however, comparing the fill-power and fill weight between different bags is a useful way to compare warmth. For example, an 800 fill power bag with a 16 oz fill weight will almost certainly be warmer than an 800 fill power bag with 12 oz of down.
A recent trend in down sleeping bags and garments is to market hydrophobic down. From the Greek meaning "water-fearing," this is down that receives a proprietary chemical treatment intended to make the feathers resist absorbing water and reduce drying time. Some companies have claimed that their treated down "stays dry ten times longer, retains 170% more loft when exposed to moisture, and dries 33% faster than untreated down". Our only problem with statements like this is that they tend to be quite vague, and rarely specifically say what those numbers compare.
In our side-by-side tests we unable to replicate results even close to these claims. In the "lab" as well as used 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 than untreated down. In our "full soak test," there was even less of a difference with more similar drying times.
Interestingly, the two best-performing manufacturers in this review—Western Mountaineering and Feathered Friends—do not currently use hydrophobic down. Separately, they raise questions about the longevity of chemical hydrophobic treatments and emphasize that high-quality down already contains natural water-repellent oils . With so much uncertainty about the benefits and little difference observed in our real-world tests, we don't believe hydrophobic down is currently worth factoring into your purchase decision. If moisture is truly a concern for you, avoid down and buy synthetic.
Down is 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. Many animal rights activists consider live-plucking to be a cruel practice, especially because it repeatedly happens to the same bird. In response, many outdoor manufacturers now use down that is only harvested humanely from non-force fed or live-plucked birds. For more on ethical down, check the two primary certification protocols for humane down the Traceable Down Standard and Responsible Down Standard.
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, preserving its warmth and temperature ratings for years to come. In the short term, keeping down bags dry is essential for them to function as an insulating layer during your trip. However, if it does get soaked, it isn't necessarily bad for it over the long-term. You might have to endure a few cold nights before being able to dry it out again.
Regardless of insulation type, all sleeping bags should stay at home in a large, breathable storage bag where the down or synthetic insulation is not even partially compressed. If your bag didn't include a storage sack or you happen to lose it, many bags also have sewn loops on the hood and footbox for hanging in a closet uncompressed. Washing down bags with a very mild soap designed for washing down garments (i.e., no detergent) and sleeping bags is essential. Western Mountaineering and Feathered Friends both have excellent pages dedicated to the proper 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 down counterparts. For example, if you put a big hole in the shell of your synthetic bag, nothing will come out, unlike a down model that will immediately start to lose feathers.
Synthetic bags are also easier and less stressful to wash because the insulation does not tend to clump when wet. However, the nature of synthetic fibers leads them to deteriorate more quickly than down. It is imperative to avoid compressing these bags for an extended period, as the more the fibers get squeezed, 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 because down feathers can withstand significantly more compression cycles than synthetics.
When it comes to the packed size of a sleeping bag, smaller is always better. However, in our tests, we discovered that the compressed volume of the bag corresponded very closely with its weight. This relationship means that although packed sized is an important characteristic of sleeping bags, if you have already factored weight into your decision, packed size is largely a redundant consideration.
Compression and Stuff Sacks
For this review, we define a compression sacks as a sack that uses buckles and straps, or some other mechanical advantage, to compress a sleeping bag into a compact size. Stuff sacks, in contrast, depend on the strength of your own hands to stuff a sleeping bag into a simple sack with a drawstring closure. Both types of sacks can be used to store the sleeping bag in your pack, but a compression sack is much better compressing a bag into a compact size.
If your bag doesn't include a compression sack and space is at a premium in your pack, get yourself an appropriately sized compression sack. For advice on that choice, see our excellent article on selecting the best compression sack.
Tips and Tricks
- To prevent the footbox of your bag from absorbing condensation from the tent wall wrap the bottom of your bag in your hardshell jacket. How: close the jacket's front zipper, tuck the hood and arms inside, and slide the jacket over the foot of the bag. This action is more important with down bags than synthetic, only don't try it if your jacket is wet. Keep the jacket's arms out and open the pit zips if you find that the jacket isn't breathing enough.
- 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. Finally, the famous adage that it's warmer to sleep naked inside a sleeping bag is simply wrong. Getting into a bag nude may warm the bag quicker, but warmth throughout the night will be lower.
- 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 system will keep the contents of your pack dry even if it gets submerged.