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Our experts have tested 27 of the best winter down sleeping bags side-by-side over the past 8 years. Purchasing 13 of the best and warmest models available today, we spent months of winter camping while sacrificing the comforts of a warm house. Tried and tested by ski patrollers, road trippers, and climbing dirtbags in the mountains through the cold months in California's High Sierra, we've got a pretty good handle on which bags are warm and which don't stack up. We meticulously evaluate key performance metrics to score each product. Our comprehensive review offers recommendations based on proven performance for those seeking to save a buck and for those seeking the best bags of feathers on the market.
Weight: 2.85 lbs | Fill: 30 oz of 850-fill goose down
REASONS TO BUY
Stellar warmth-to-weight ratio
REASONS TO AVOID
The Western Mountaineering Kodiak MF is an excellent cold weather bag. WM has been quietly churning out this bag to a devoted following of adventurers for years. All of the Western Mountaineering bags in this review feature huge 3D draft tubes and snag-free zippers. This bag rises to the top because of its super comfy 66-inch cut in shoulders and its 30 ounces of 850 fill down. It's our favorite balance of warmth, weight, and comfort for winter camping in the mainland United States. Our testers loved that they could sleep on their stomach, side, or back without skipping a beat AND hold all of the gear that needs to be insulated, all while staying comfortable. It also packs down small.
Extra room in a sleeping bag is nice if you're going to be spending weeks under the stars, but keep in mind that uninsulated space won't feel as warm as a tighter-fitting bag. You can remedy this by stuffing your extra layers and jackets in the bag with you. Western Mountaineering bags are the gold standard, but they're expensive. Care for it, though, and this high-quality model could last decades of winters.
Weight: 2.68 lbs | Fill: 29.6 oz of 850-fill goose down
REASONS TO BUY
Small storage pocket for headlamp or batteries
High-quality stuff sack included
REASONS TO AVOID
Could be a tight fit for some
The Mountain Hardwear Phantom 0 has been tweaked and redesigned over the decades. However, it remains one of the highest quality bags on the market and is still highly coveted by anyone who dreams of spending nights out in a wilderness of white. Featuring 850-fill power down in a 10D recycled nylon shell, this highly compressible, sub-3-pound bag is perfect for winter backpacking trips and overnight ski tours. Speaking of compression, MHW pulls out all the stops, including a high-quality compression sack with this bag. Our testers appreciate the DWR treated shell fabric that keeps the down dry and protected from condensation, and they also love thoughtful features like the storage pocket, and glow-in-the-dark zipper pulls.
Though the cut of the Phantom 0 is standard compared to most of the top-performing down bags, larger folks may find it a little tight, especially if they're spending multiple days in a base camp situation, keeping a liter of water, a set of clothes, or even their boots in the bag with them. There's also no getting around the price on this bag, as quality goose down doesn't come cheap, especially when encased in a lightweight and durable shell fabric. Hopefully, if you pony up for the Phantom, your excuses not to get out in the backcountry this winter will disappear, as will any buyer's remorse. We'd bet on it.
The Mountain Hardwear Bishop Pass is an affordable bag that outperformed other similar bags in the mid price zero degree field. It has an oversized draft tube and a plush draft collar that is ergonomically shaped to trap heat in and keep cold air out. The DWR treated shell performed swimmingly in our light rain and soaking testing and withheld from saturation much longer than other products in its class. It boasts a significant amount of fill but isn't overly heavy, thanks to its overall slim shape.
This bag is a mummy shape that could feel tight for larger users. Our largest testers weigh in at 200 pounds and are six feet tall; they had no problems getting comfortable in every sleeping position. It is heavier than more expensive bags in this temp range; however, for the price, you won’t think about the extra ounces, especially if you aren’t going too far. This is an excellent four-season bag for car campers or adventurers on a budget. Extra features like a glow-in-the-dark zipper and stash pocket rounded out our love of this bag over the competition.
Narrow cut for thermal efficiency and weight savings
Awesome snag-free zipper
REASONS TO AVOID
Not as resistant to rain and snowmelt
Impressive warmth falls noticeably short of heavier models
The Western Mountaineering Versalite is our go-to bag for ultralight winter adventures. Weighing in at a scant 2 pounds 1 ounce, this bag has an excellent warmth-to-weight ratio and is fantastic for spring ski tours and chilly climbing trips. As with all Western Mountaineering bags, the Versalite has a great snag-free zipper, a lofty draft tube, and a warm draft collar. Paired with a down jacket, the versatile Versalite is a superb choice for those who tend to sleep warm and want to cut weight.
The Versalite isn't as weather-resistant as some of the heavier bags in this review, but it packs down smaller and weighs less than every bag in its class. If you're consistently facing temperatures colder than the mid-teens and below, we'd suggest carrying a warmer or heavier bag, like the Mountain Hardwear Phantom 0 or the Western Mountaineering Kodiak. If not, this bag is worthy of falling in love with.
Not as warm as other bags rated to the same temperature
The Nemo Sonic earns a spot in the winner's circle for its overall comfortable design. The generously wide-cut gave our testers plenty of room to toss, turn, and sprawl inside this bag. Thermal vents allowed us to dial in just the right amount of warmth for a wider range of usefulness (though it was so cold through most of our testing that we opted to keep them closed). Additionally, the deep hood, wide shoulder cut, and elastic foot box allowed our testers to change clothes while still inside the bag.
Our testers feel the Sonic isn't as warm as some of the other 0-degree F bags in our review, most notably the Western Mountaineering Kodiak MF. Because of the extra room, this bag isn't as thermally efficient as some of the tighter-fitting bags. A good way to add a little warmth is to stuff your puffy jacket in the bottom of the bag to fill up the extra space. If comfort is your top priority, this could be the bag you've been looking for.
Super wide cut for storing boots, water, or extra clothing
Reinforced inside the toe box to resist damage from boots
REASONS TO AVOID
Takes up lots of space in a backpack
The Marmot Col is a great bag for expeditions, where you'll likely spend days on end inside your sleeping bag, staying warm and waiting for good weather. This bag has plenty of room to store water bottles, boots, extra clothing, and anything else you don't want to freeze. This bag is so spacious that one of our testers found he could even read while remaining entirely inside.
The Col weighs over 4 pounds and doesn't pack down as small as lightweight bags in our review, so this isn't the best choice for long-distance human-powered activities. This is a better choice for folks getting around on a snowmobile, horse, or dogsled. If comfort, weather resistance, and warmth take priority above weight and packability, the Col is a perfect choice for your winter base camp.
This review is brought to you by Ryan Baker, Matt Bento, and Jeff Rogers. Ryan enjoys cozying up in the wilderness, from cold Sierra Ridges to frigid alpine glaciers of Alaska. He’s traveled high and low as a mountaineer, skier, and climber through nearly every latitude and hemisphere. Matt has spent more of his life in a sleeping bag than he cares to admit, working in wilderness therapy and as a backpacking guide, and during his personal backcountry climbing pursuits. He's used roomy bags for weeks of living out in the snow and more lightweight bags for alpine missions in the Sierra. An ambitious skier, Jeff has many big ski descents under his belt, traveling everywhere from Alaska to Bolivia to pursue big lines. These adventures take him deep into the backcountry, where he appreciates a sleeping back that is light and warm.
Discovering the best down bags began with scouring the market for the most popular models. Then we purchased and evaluated the top candidates, scoring them with our metrics of warmth, weight, comfort, packed size, features, and weather resistance. We tested these bags primarily in the Sierra Nevada mountain range of California while also taking them on trips in New England in the dead of winter. After 100s of zipped zippers, packed backpacks, and plenty of chilly nights under the stars, we feel confident in our recommendations.
Analysis and Test Results
A key piece of gear in every person's overnight winter kit is their sleeping bag. Without it, you will likely succumb to the extreme cold while trying to catch some sleep. Another great way to visualize your sleeping bag is that it's your "survival capsule." If you were to accidentally rip a hole in your tent or break your leg far away from the nearest help, your sleeping bag will likely be the difference between staying safe and getting rescued or becoming hypothermic while waiting to be rescued. In most situations, you just need the ability to burrow inside a lofty down cocoon at the end of a cold day and get warm. Remember, on winter trips where building a fire isn't an option, you may have no other heat source besides your own body heat. Thankfully, modern down bags allow us to stay alive and even sleep comfortably in the coldest conditions with waterproof/breathable fabrics, hydrophobic down materials, and various clever design strategies. The ability to not only fall asleep but also rest and recover adequately is key to enjoying any of the skiing, hiking, or climbing you plan on doing during your trip. Shivering all night and surviving is one thing, but slumbering into a deep sleep to wake up refreshed is another.
Our review selection includes bags that will keep you warm and comfy in the parking lot of your favorite winter crag, as well as high-end, lightweight bags suited for climbing expeditions and backcountry ski tours. We brought back some tried-and-true favorites from our previous review and pitted them against a range of newcomers. We evaluated each bag for its warmth, weight, comfort, packed size, features, and weather resistance.
A key part of purchasing a new winter bag is ensuring it fits within your budget constraints. To remain objective about performance, we didn't factor value into a product's score, but we still understand that it's a top consideration for most buyers. A big trade-off in this category is the quality of the down fill and the loft it provides. The less expensive bags generally weigh more and loft less, leading to a heavier pack and a less warm bag. But, to save a few hundred dollars (or more), you might be willing to haul a tad more weight and sleep with your puffy on (which is more than likely with you on any winter trip). This is a personal choice, but one worth wrestling with. Also, consider the use case of this sleeping bag. Being as realistic as possible, how often are you sleeping in this bag? Once or twice a year? Ten times a year? 50 times a year? A top-dollar sleeping bag may not seem like much of an expense when you divide its price by 50 nights.
Alternatively, if you're only using it a couple of times a year, you don't need the highest-end materials and fabrics. The Mountain Hardwear Bishop Pass offers excellent warmth for the price without breaking your back on the ascent. While it's more expensive than the Kelty Cosmic Down 0, we think it's worth this price bump for better overall performance, features, and a higher down fill rating.
A sleeping bag's warmth stems from a few different factors. The bag's fill power, the fill weight, and the bag's cut most dramatically affect how warm a sleeping bag is. A bag with a high loft (a combination of fill weight and fill power) will keep you warmer because there will be more insulated air between you and the cold air outside. This insulated space allows you to create a warm microclimate with your body heat. The bag's cut or fit determines the dimensions of the shoulder, hip, and foot box, which can feel tight or roomy depending on a person's body shape. Extra space can be useful for accommodating additional layers you may want to wear or items you want to keep warm with you through the night, like water bottles, radios, headlamps, phones, white gas, stoves, boot liners, and batteries. However, with the added airspace a larger cut bag provides, there is more uninsulated space inside the bag, which is less thermally efficient. It will take longer to bring the sleeping bag from the ambient temperature to a suitable body heat temperature and feel warm inside. You will also have an easier time noticing any drafts that make it past the draft collar.
The warmest bags in our selection are the bags with the most loft and the most fill material. The Marmot Col -20 houses an impressive 44 ounces of 800 fill power down and features a wide cut, with plenty of space for wear/storing extra layers. Our testers found they could even change clothes inside the bag. This is a bag geared toward more extreme temperatures that the vast majority of winter campers are less likely to experience, though, so its extra warmth might not be necessary.
The Western Mountaineering Kodiak MF feels less warm while being much lighter than the Marmot Col. It has less room but is significantly wider than the similarly rated Snowbunting and Antelope. It is a great option for those who value roominess and want to have plenty of insulation to keep them warm at 0F.
For those looking for maximum thermal efficiency, there is the Feathered Friends Snowbunting, one of the slimmest bags in our review. The Snowbunting packs 25.3 ounces of 900 fill down into a 2.8-pound package.
The Western Mountaineering Antelope MF, the Rab Neutrino 800, and the uber comfy Nemo Sonic are similarly rated and weighted bags, but the Rab Neutrino 800 and the Antelope feel warmer than the Nemo Sonic because they both have more down and narrower fits. The Western Mountaineering Versalite, conservatively rated to 10 degrees, is the lightest bag in our review but is still warmer than the heavier Nemo Sonic due to its high loft and narrower cut.
Less expensive bags like the Mountain Hardwear Bishop Pass, Rab Ascent 900, and Kelty Cosmic Down 0 can feel as warm as some of the higher-end bags. The good news is that you can sleep out in the lower temps at a lower price. The Kelty Cosmic Down 0 is as warm and lofty as the Rab Ascent 900, but you'll pay with your legs, back, and the space in your pack. The Bishop Pass is nearly as warm as higher-priced competitors, which is a big reason it gets our attention as a stellar budget-focused purchase.
A sleeping bag's total weight is a function of its fill material and the weight of its shell fabrics. There are two important indicators in our tests: the fill weight and the weight of the rest of the bag. You can compare this ratio against other bags to see how warm the bag is for its weight. A bag with higher quality down filling (800 or more) can achieve a lower temperature rating at a lower weight. High-tech shell fabrics allow for weather resistance and durability, even in light, 12 denier shells. Light is right if you're going the distance! But it's usually costly.
The lightest bag in this review is the Western Mountaineering Versalite, with its super thin 12-denier Extremelite shell. The Versalite boasts 20 ounces of 850 fill goose down and weighs in at 2 pounds 1 ounce; it has an excellent warmth-to-weight ratio but isn't as weather-resistant as the heavier Feathered Friends Snowbunting. The welterweight Western Mountaineering Antelope MF tips the scale at 2 pounds 10 ounce, similar to the Nemo Sonic, but the high-quality lightweight shell allocates more of that weight to insulation, so it feels warmer. It's important to also look at what kind of environment the bag will be experiencing. Maybe getting a more weather-resistant shell makes sense if you often face damp climates during your winter excursions.
The warmest bags in our selection are also some of the heaviest. The Marmot Col -20 weighs 4.08 pounds, dedicating 21.3 ounces to its tough, highly weather-resistant 30-denier Pertex shell fabric. The Western Mountaineering Kodiak MF (2.85 pounds) cuts off a few ounces while still having a wide fit and great features due to its light shell fabrics. The Mountain Hardwear Phantom 0 deserves recognition regarding its weight. It feels pretty equal to the Kodiak in warmth but weighs almost three ounces less.
The Kelty Cosmic Down is one of the most affordable and also one of the heaviest bags we tested, weighing 3.8 pounds — on par with the Marmot Col's weight, but not even close in terms of warmth and weather resistance. The Mountain Hardwear Bishop Pass isn’t a brick weighing in at 3.21 pounds. Its competitive weight and warmth make it a budget-friendly steal.
We determine comfort based on the feel of the bag against our skin, how the hood and draft collar fit, and, most importantly, how much space is in the bag. Sleeping bags with a wider cut generally received higher comfort scores. If you sleep exclusively on your back, a wide cut isn't too much of a concern. For some of our testers who spend their nights in a bag for weeks on end, room to sleep on their sides and stomachs is critical. The price of comfort? Extra fabric equates to extra weight and less space in your backpack. Consider how well you perform after a poor night of sleep, and you may decide the extra weight is worth it.
The Nemo Sonic has one of the roomiest cuts of all the bags we tested. While its shoulder girth isn't the widest of all we tested, its hip girth is, which is helpful for those who like to curl up in their sleeping bags. Our testers found they could sleep comfortably in this bag in any position, even in the classic "can opener" position, due to the cut and the slight stretchiness of the fabric. There's also a ton of extra space at the foot of the bag, making room for hot water bottles and damp clothes you want to dry out. The generous dimensions of the WM Kodiak were appreciated by all testers, too, coming in just behind the Sonic in all-night comfort. The Marmot Col is also wider in the shoulders and hips than most models. For trips lasting more than a couple of nights, or frequent winter trips, we recommend considering comfort strongly in your purchase decision, as the importance of nighttime comfort increases with each night spent in a wintery backcountry environment.
The Western Mountaineering Versalite and the Antelope lost points in this metric due to their shallow hoods. Our testers generally preferred the slightly deeper hood of the Kodiak with drawstrings for the hood and the draft collar. The lower scores in the comfort metric go to the Feathered Friends Snowbunting and the Kelty Cosmic Down 0. The Snowbunting and the Cosmic Down have shallow hoods and relatively narrow (but thermally efficient) cuts. These bags didn't score very high here but are by no means uncomfortable - simply average. Again, the width isn't so important if you primarily sleep on your back. Additionally, if you're interested in the Snowbunting for alpine and big wall climbing, you'll likely be on your back anyway, sleeping on a narrow ledge or nestled among the rocks. Conversely, if you are spending weeks climbing Denali or weeks camping in remote and cold locations, a thermally efficient cut can get tight quickly. With the added amount of items needed to sleep with and the overall longevity of time spent in your sleeping bag, it makes sense to go with a wider cut like the Sonic, Kodiak, or Marmot Col.
Ski touring can be a gear-intensive activity, and pack space is a premium once you've accounted for a shovel, probe, food, water, layers, and a tent—ditto for alpine climbing, when you may find your pack overflowing with ropes and cams. Higher quality materials are critical for increased packability. To assess the packed size, we crammed each bag into our Sea to Summit compression sack and pulled down as hard as we could on the compression straps. We then got an accurate idea of how each sleeping bag compressed in the same stuff sack, as well as how they compressed in their own stuff sacks when the manufacturer included them.
Much to our surprise and delight, each bag fit inside the compression sack, even the hulking Marmot Col, which looks huge when lofted in its storage sack. The ultra-light Western Mountaineering Versalite predictably compresses the most. We found it easiest to compress the bags by sitting on them once they were in the stuff sack; you can then rotate the compression sack and tighten each strap. The Western Mountaineering Kodiak MF packs down to a backpack-friendly size, even though it's one of the wider and warmer bags in the review. This is why we love the Kodiak so much; a ton of loft and room with a manageable packing size.
Bags with a lower fill power down take up the most space. The Kelty Cosmic Down 0 is one of the least packable, taking up more room than the Marmot Col.
Features are a subjective, multifaceted metric, comparing aspects universal to all the bags, such as draft tubes, hoods, and zippers, while also factoring in characteristics unique only to certain bags. Some bags had stash pockets, which are useful for storing batteries or a watch but also can be annoying if you roll over on them. Some sleeping bags also had two zippers so you could sit up while still inside the bag. Other bags had "gills" to allow you to vent at the base of the climb, where you may not encounter conditions even close to 0F. All of these features were considered when scoring a bag.
The Nemo Sonic has a ventilation system employing two zippered gills on the top of the bag, so you can cool off when using the bag in warmer weather. We feel this is an interesting feature but do not like the fact that if the zipper breaks, you are now in a 20F bag regardless of how cold the nighttime low is. The Western Mountaineering bags are a standout for their awesome snag-free zippers, while other zippers snagged on the double draft tubes.
A few bags had a small pocket inside the bag for keeping small items accessible and items with batteries warm such as the Mountain Hardwear Bishop Pass. Bags with simple, practical features scored higher. Bells and whistles are great, but they can cause problems when they break, and they also add unnecessary weight. So if the feature set was well thought out, reliable, and didn't add significant weight to the bag, those scored the highest. The top scorers in this metric are the Marmot Col -20 and Nemo Sonic, pumping out the features.
Due to the variety of conditions that can be encountered on a climb, a sleeping bag must be able to withstand wet weather. Condensation from tents, frost from your breath freezing on the inside, and even a light rain shower are all realities your sleeping bag might face on a multi-day climb. When down gets wet, it loses its loft because the down clusters can no longer trap air. This results in a total loss of insulating properties.
Alternatively, if a bag can withstand the elements well enough on its own, you get a bonus weight savings since you don't have to bring along a bivy sack or a tent. A sleeping bag's weather resisting abilities boil down to shell fabrics. The variety of shell fabrics on the market make some down sleeping bags suitable for use out in the open, others made for the shelter of a tent. Some of the bags feature specially treated hydrophobic down.
The manufacturers claim hydrophobic down absorbs less water, maintains its loft better, and dries out faster than untreated down. Our testing team could distinguish a difference between treated and untreated down in some of the sleeping bags with a more delicate face fabric. We found that the sleeping bags with a thick waterproof shell didn't seem to need hydrophobic down as it was hard to get the down inside the bag wet at all, short of sticking the garden hose inside the bag. They were just that waterproof. The Rab Neutrino 800 and the Rab Ascent 900 feature down with a hydrophobic treatment.
The Marmot Col -20 is king in combating adverse weather. Its burly, waterproof shell absorbed zero water, even in our submersion test. The Feathered Friends Snowbunting falls right behind the Marmot Col. These contenders kept our testers warm and dry in light rain. And something to note, none of these bags contain hydrophobic down. The best bags for cowboy camping just have excellent shell fabrics. Even the lightweight Western Mountaineering bags were impervious to light rain and condensation. We want to stress how high-tech these fabrics are nowadays and that you don't need a full membrane for most applications.
Only the Kelty Cosmic Down 0 absorbed enough rain to soak through to our testers. If you decide to purchase this warm, budget-friendly bag, make sure you've got an effective way to keep it dry, like a tent or the back of your car.
A stuff sack and a storage sack are included with each of the bags in this category, except the Kelty Cosmic Down 0, which only comes with a stuff sack. The Western Mountaineering bags have the largest storage sacks, allowing you to store them at the maximum loft. The Rab Ascent 900 and Nemo Sonic include a stuff sack with compression straps, and the Rab Neutrino 800 comes with a dry bag. Some sleeping bags come with a compression sack, which is useful for getting the smallest form factor out of your sleeping bag. The Phantom 0 comes with a compression sack, decreasing the packed size while increasing value since you won't have to purchase an aftermarket sack. In some scenarios, though, stuffing the bag directly into the backpack can yield the best results, negating the need for a stuff or compression sack.
Be sure to purchase a quality sleeping pad that will keep your body warmth in. All the expensive, high-quality down is useless if it's compressed underneath your body, with only a thin shell layer between you and the frozen ground. To complement a winter down bag, you'll need a pad that's light, durable, and insulates well. Look for an r-value of at least 5, or use a combination of a foam pad underneath an inflatable pad. Alternatively, some high-end sleeping pads do not require the addition of foam underneath.
We hope we've unraveled some of the mysteries around selecting the best cold weather sleeping bag to suit your specific needs. While a good down sleeping bag may seem like a huge financial investment, it should keep you warm and cozy for years if properly cared for, and nothing beats a good night's sleep under the stars on a long winter's night.
Introduction Backpacking equipment is generally the same...
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