Best Backpacking Sleeping Bags of 2025
ByMultiple Authors
Updated:
Jul 24, 2025Updated:
Jul 24, 2025Table of contents
Sea to Summit Spark 15 ($549)
Feathered Friends Swallow UL 20 ($629)
REI Co-op Magma 30 ($349)
Kelty Cosmic Down 20 ($180)
Nemo Disco 30 ($270)
Mountain Hardwear Bishop Pass 30 ($245)
Therm-a-Rest Boost 650 20 ($320)
The Spark is all about simple design and premium materials, and this light, warm mummy bag is packable enough for any backpacking trip. Some sleepers may find its lack of bells and whistles slightly disappointing for the high price.
The Spark is all about simple design and premium materials, and this light, warm mummy bag is packable enough for any backpacking trip. Some sleepers may find its lack of bells and whistles slightly disappointing for the high price.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
29/15°F (ISO Comfort/Limit)
Other Temps
0, 30, 45F
Weight
1 lb. 9.7 oz.
Fill
1 lb. 0.9 oz. of 850-fill down
Pros
Cons
Weighing just over one-and-a-half pounds and packing in over a pound of 850-fill-power down, the Spark 15 possesses one of the best warmth-to-weight ratios of any sleeping bag we tested. Its performance is right up there with category stalwarts such as the Feathered Friends Swallow UL 20, making it a fantastic three-season model for backpackers who want a light, packable bag that will keep them reliably cozy. The Swallow UL 20 also contains just over a pound of down, but it's more insulating for the weight at 950 fill power. If the Feathered Friends is the only bag to best the Spark though, rest assured (literally) that the bag is in good company.
Although the Sea to Summit Spark 15 is fairly roomy up top with a 61-inch shoulder girth, it sports a classic mummy shape that tapers sharply towards the 40-inch footbox. Our tester—who deemed the Spark so comfortable he slept in it instead of blankets in an Airbnb in Norway—found the bag plenty roomy, but side-sleepers and campers who toss and turn may be more constricted. However, this is true of pretty much all mummy bags, and opting for a semi-rectangular bag would negate the Spark’s packable, minimalist appeal. Speaking of which: Although it doesn’t have many features we appreciate on modern bags (no zippered pockets, vents, etc.), the Spark’s zipper is a true standout. Ultralight bags tend to have finicky zips that can rip their thin fabric, but the Spark’s has a chunky “plow” that allowed our tester to never hit a snag.
Our only real concern with the Spark is its 10-denier nylon fabric, which can easily rip if you’re not careful. This problem comes with the territory and is one that many ultralight bags face. The nylon is plenty comfortable on the skin, though, and our tester shouted out one more user-friendly factor: Thanks to a handy snap system at the neck, you can use the Spark as a quilt when it’s fully unzipped. This increases the bag’s versatility and adds another feather to the cap of one of our favorite lightweight bags on the market. For more, read our review of the Sea to Summit Spark 15.
It’s easy to love this bag’s impressive combination of warmth, low weight, roominess, and packability. The Swallow UL’s price tag isn’t for the budget-conscious, but for serious backpackers, it’s well worth the spend.
It’s easy to love this bag’s impressive combination of warmth, low weight, roominess, and packability. The Swallow UL’s price tag isn’t for the budget-conscious, but for serious backpackers, it’s well worth the spend.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
20°F (not ISO rated)
Other Temps
30F
Weight
1 lb. 11.3 oz.
Fill
1 lb. 0.8 oz. of 950-fill down
Pros
Cons
Feathered Friends may not have the widespread name recognition of brands like Big Agnes and Nemo, but this Seattle-based manufacturer—which specializes in high-end down products and sells direct-to-consumer—boasts one of the most impressive sleeping bag pedigrees in the industry. The company’s commitment to dialed design and premium materials is fully evident in the Swallow UL, one of the best three-season bags money can buy. (You’ll need a fair bit of cash to make it yours, though.)
The Feathered Friends Swallow UL is packed with just over a pound of 950+ fill-power down, the warmest and most compressible down we’ve tested. As a result, it compresses impressively small while still delivering a spot-on lower limit temperature rating of 20 degrees Fahrenheit. While the Swallow UL doesn’t lead the category in warmth-to-weight ratio—for example, the Sea to Summit Spark 15 weighs only 1 pound 9.7 ounces—its packability might be unmatched. (As always, using a compression sack can further reduce packed size.)
Another key feature is the Pertex Endurance shell, which utilizes a silicone-based DWR for enhanced water resistance. However, the 10-denier fabric is relatively thin and should be handled with care inside and outside of the tent (for comparison, the Western Mountaineering UltraLite features a more durable 12-denier nylon shell). And then there’s the price: the Swallow UL costs $1 less than the UltraLite (woohoo!) but $80 more than the Spark and roughly $200 more than the Nemo Riff Endless Promise 15 and REI Co-op Magma 15. While the Riff and Magma are heavier and less packable, they’re also more modern, featuring a full draft collar and ventilation options—two things the Swallow lacks. But for the essential combination of warmth, packability, and weight, the Swallow UL remains one of the top contenders in the three-season sleeping bag market. For more, read our review of the Feathered Friends Swallow UL 20.
REI brings premium sleeping bag design to the masses with Magma, an 850-fill power model that boasts an extremely reasonable price point. Throw in a plethora of size options—the most of any model we’ve seen from a major brand—and there is a lot to like about this bag.
REI brings premium sleeping bag design to the masses with Magma, an 850-fill power model that boasts an extremely reasonable price point. Throw in a plethora of size options—the most of any model we’ve seen from a major brand—and there is a lot to like about this bag.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
34/24°F (ISO Comfort/Limit)
Other Temps
15F
Weight
1 lb. 8.4 oz.
Fill
12.7 oz. of 850-fill down
Pros
Cons
REI’s in-house gear often leans toward the value end of the spectrum, but the Co-op occasionally dabbles in premium products—and the Magma line of sleeping bags has been one of its most successful high-end offerings since its 2019 release. The Magma 30 (also available in a 15-degree version) is filled with 850-fill-power goose down and comes in a wide range of lengths and widths (more on that below). It also offers an unparalleled price for hikers looking for a high warmth-to-weight ratio without breaking the bank. Compared to premium brands like Feathered Friends or Western Mountaineering, the Magma is at least $200 cheaper.
So, what’s the catch? While the REI Magma 30 is a quality backpacking sleeping bag, it feels like a notable step down from other high-end options. Despite its high fill power, it’s bulkier than competing ultralight bags, which becomes particularly noticeable when packing it into its stuff sack. Additionally, we’ve found that the Magma runs a bit cooler than its listed temperature rating, and the draft collar is floppy and awkward when the bag isn’t fully zipped. Ultimately, while the Magma 30 has some premium features, it feels more mid-range than high-end, aligning well with its competitive price point.
On the plus side, REI offers an impressive range of unisex sizes—nine in total—which is a rarity outside of made-to-order cottage brands. The short version fits up to 5’5”, the medium up to 5’11”, and the tall up to 6’5”, with each size available in narrow, medium, and wide variations. This level of customization allows backpackers to fine-tune their fit, which not only improves comfort but also maximizes warmth efficiency. The Magma 15-degree version follows the same sizing system, making it one of the most adjustable off-the-shelf options available. For more, read our review of the REI Co-op Magma 30.
With some of the best price-to-performance on the market, the Cosmic Down is a solid value bag for backpackers who still want good warmth and decent packability. But with a higher-than-average weight and packed size, it’s a stretch to call it a suitable fit for longer backpacking routes.
With some of the best price-to-performance on the market, the Cosmic Down is a solid value bag for backpackers who still want good warmth and decent packability. But with a higher-than-average weight and packed size, it’s a stretch to call it a suitable fit for longer backpacking routes.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
31/21°F (ISO Comfort/Limit)
Other Temps
0, 40F
Weight
2 lb. 7 oz.
Fill
1 lb. 0.4 oz. of 550-fill down
Pros
Cons
The Cosmic Down might be our favorite low-cost sleeping bag, although you need to put that in perspective. It can’t match the warmth-to-weight ratios or feature sets of more expensive models, but then again, it’s not meant to. This budget sleeping bag is designed as a serviceable, moderately packable option for backpackers who aren’t going to stray super far from the trailhead. In that sense, it fills its niche quite well and is roomy enough for use as a car-camping sleeping bag if you really want to max out its value.
What puts the Kelty Cosmic Down 20 ahead of similar budget models such as the Marmot Trestles Eco Elite 20 and the REI Co-op Trailmade 20 is that it’s stuffed with down insulation rather than synthetic. Sure, the Cosmic’s Down’s 550-fill power plumage isn’t lofty compared to the fill of more premium bags, but it's still more packable than synthetic fill. Our tester, who used both the Trestles Eco Elite and the Cosmic Down on an overlanding trip in the Pacific Northwest, deemed the former more lofty when unfurled, although she noted that both bags fall short of their stated temperature ratings. She put the Cosmic’s limit closer to its 31-degree comfort rating, which feels right given the price point.
Construction-wise, the Cosmic is a fine sleeping bag—and we mean that as a compliment. Both its outer and inner materials feel soft, and the zippers are of good quality and run smoothly. Our tester also praised the bag’s warm hood and small zippered pocket. Last but not least, the large footbox is a nice design element, so this is not a featureless bag that tosses livability out the window. If you’re just breaking into backpacking and don’t need the lightest or most packable sleeping bag, the Cosmic is a good starter to get as a keystone of your first kit. For more, read our review of the Kelty Cosmic Down 20.
With an hourglass shape that provides plenty of room at the shoulders and knees, the Disco’s dimensions are a boon for side-sleepers. We also like its thoughtful design choices and soft materials, although its durability and weight aren’t top notch.
With an hourglass shape that provides plenty of room at the shoulders and knees, the Disco’s dimensions are a boon for side-sleepers. We also like its thoughtful design choices and soft materials, although its durability and weight aren’t top notch.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
40/30˚F (ISO Comfort/Limit)
Other Temps
15F
Weight
2 lb. 2 oz.
Fill
11 oz. of 650-fill down
Pros
Cons
The Disco’s unmistakable silhouette is one of the most recognizable designs in the sleeping bag world. Its hourglass shape—which flares at the shoulders (62-in. girth) and knees (61-in. girth)—invites side sleepers to get comfortable. Unlike a svelte mummy bag, the Disco allows you to curl up, move side to side, or turn over mid-sleep without feeling trapped.
Beyond its spacious design, the Nemo Disco 30 has several comfort-forward features. Our tester—who sleeps warm—came to appreciate its two torso vents, which have zippers on both the inside and outside, allowing for easy temperature regulation without opening the bag. (The vents aren’t pass-through and are covered by thin material.) She also raved about the draft collar, calling it her favorite feature. The generously filled collar folds up and down at the bottom of the hood, sealing out cold air while providing an extra-cozy shot of floof (her word, not ours).
The Disco’s silky-smooth polyester shell is another highlight—quiet, soft, and pleasant against the skin. However, it’s not the most durable bag we’ve tested. We noticed some abrasions and feather loss, though we admittedly weren’t as careful as we could have been. As for warmth-to-weight, the Disco’s 650-fill-power down isn’t particularly impressive—many 30-degree bags are lighter, and some 20-degree models weigh even less. That said, the Disco is far more affordable than those ultralight alternatives, none of which match its smartly designed dimensions and comfort-focused extras. Sometimes, it’s worth ditching the “light is right” mentality and letting comfort take center stage. For more, see our review of the Nemo Disco 30.
Despite its no-frills mummy design, there’s much to like about the reasonably priced Bishop Pass. It’s not supremely light or packable, but it’s a good value buy for hikers who sleep in relatively balmy three-season temps.
Despite its no-frills mummy design, there’s much to like about the reasonably priced Bishop Pass. It’s not supremely light or packable, but it’s a good value buy for hikers who sleep in relatively balmy three-season temps.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
40/30˚F (ISO Comfort/Limit)
Other Temps
0, 15F
Weight
1 lb. 12.6 oz.
Fill
12.3 oz. of 650-fill down
Pros
Cons
Mountain Hardwear isn’t best known for sleeping bags, but the Bishop Pass is a respectable entry into the category—especially at its price point. While it doesn’t push any design boundaries, its tried-and-true mummy shape and lower-fill-power down provide dependable performance. Consider the Bishop Pass if you don’t expect to encounter below-freezing temperatures, don’t mind carrying a little extra weight, and want to stick to a budget without resorting to ultra-budget models like the $170 Kelty Cosmic Down 20.
One of the Bishop Pass’ biggest strengths is its durability. One Better Trail tester immediately noted its rugged 30-denier nylon shell, which provided peace of mind even when lounging outside her tent on Washington’s granite-heavy terrain. A sleeping bag that offers long-term durability alongside warmth is always a smart investment, and the Bishop Pass 20 sweetens the deal with a two-way, anti-snag zipper, a glow-in-the-dark zipper pull (perfect for midnight bathroom trips), and a small internal stash pocket. These features aren’t groundbreaking, but considering this bag costs half as much as some premium competitors, they’re impressive additions.
As expected, the Bishop Pass isn’t the most efficient in warmth-to-weight ratio or packability. Additionally, we were unimpressed with the included stuff sack, which is made from cheap, heavy material. If possible, invest in an aftermarket compression sack to make the most of its bulk, and then pass on the Bishop Pass’ savings to the rest of your backpacking kit. For more, read our review of the Mountain Hardwear Bishop Pass 30.
The versatile, uniquely designed Boost is geared toward comfort-minded backpackers who want a bag they can also use for car camping, travel, or the occasional house guest. It’s heavy for hiking far, though, and a bit expensive for its weight and bulk.
The versatile, uniquely designed Boost is geared toward comfort-minded backpackers who want a bag they can also use for car camping, travel, or the occasional house guest. It’s heavy for hiking far, though, and a bit expensive for its weight and bulk.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
32/20°F (ISO Comfort/Limit)
Other Temps
32F
Weight
2 lb. 11 oz.
Fill
1 lb. 7 oz. of 650-fill down
Pros
Cons
“Features” aren’t something we typically rave about in sleeping bags. Apart from material and dimension differences, most models look pretty similar. But every so often, a design breaks the mold—and the Boost is one of them. This bag’s standout features come in the form of three zippers: a center zipper (called the “WarmZip”) and two at the shoulders. The WarmZip transforms the Boost from a spacious, semi-rectangular bag into a more thermally efficient mummy shape—it doesn’t open or close the bag but instead draws the insulation closer to the body, reducing dead space and boosting warmth. One Better Trail editor, who tested the Boost for a month of nights in a cabin in El Chaltén, Argentina, praised the incredible temperature range. Whether the night dropped to 30 degrees Fahrenheit or soared to 70 degrees (Patagonian weather knows no bounds), the Boost adapted comfortably.
The bag’s two shoulder zippers function primarily as armholes but also function as vents. While we initially saw them as a bit of a “party trick,” they’re surprisingly useful for reading in the evening, lounging in the tent (card games, anyone?), or for those who don’t like sleeping with their arms constricted. Adding to the Boost 650 20's comfort factor, its unzipped configuration is roomy—closer to a rectangular camping bag than a mummy-style backpacking bag—and its 20-denier nylon (chosen for its soft hand feel) is luxuriously comfortable. The cherry on top? All the zippers have anti-snag casings and operate smoothly.
Of course, all these features come at a cost. The Boost’s jam-packed design and 650-fill-power down make it heavier and less packable than many true backpacking models. At over 2.5 pounds, it’s nearly a full pound heavier than some of our favorite lightweight bags. But those mummy bags can’t match the Boost’s comfort and adaptability, making it our top pick for frontcountry use. If you need a sleeping bag for the occasional short overnight, car camping trip, or even crashing at a friend’s house, the Boost is an absolute joy. For more, read our review of the Therm-a-Rest Boost 650 20.
While the Parsec is a mummy bag through and through, its streamlined shape belies its roomy dimensions and nice quality-of-life touches. However, it has slightly less-than-elite loft, and didn’t prove as warm as we’d like.
While the Parsec is a mummy bag through and through, its streamlined shape belies its roomy dimensions and nice quality-of-life touches. However, it has slightly less-than-elite loft, and didn’t prove as warm as we’d like.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
32/20˚F (ISO Comfort/Limit)
Other Temps
32F
Weight
1 lb. 12 oz.
Fill
1 lb. of 800-fill down
Pros
Cons
The Parsec is Therm-a-Rest’s most well-balanced backpacking sleeping bag, offering a solid mix of warmth, weight savings, and comfort. Thanks to its 800-fill-power down, it’s light and warm enough for most three-season backcountry adventures. But what sets it apart from typical mummy bags is its roomier dimensions. With girth measurements of 62 inches at the shoulders, 57 inches at the hips, and 46 inches at the footbox, the Parsec offers more space than many of its high-performance competitors, including the Feathered Friends Swallow UL 20 (60/56/38 in.) and Therm-a-Rest’s own Hyperion 20 (55/48.5/40 in.). Unlike more restrictive mummy bags, the Parsec provides ample room in the shoulders and hips, making it a comfortable choice for those who move around at night.
However, this extra space comes with trade-offs. We found that the roomy footbox created too much dead space, leading to cold feet when temperatures dipped below freezing. While stuffing extra clothes at the bottom of the bag helps mitigate this, it’s a good reminder that bigger isn’t always better. Additionally, the hood is difficult to cinch down, and the baffle along the zipper—while a nice addition—falls short, allowing some cold air to seep in. The Parsec is undeniably comfortable but is not the most reliable option for sub-freezing conditions.
Where the Parsec shines is in weight and packability. It comes with a compression stuff sack and packs down smaller than a 1-liter Nalgene (though it’s about twice as wide). While 800-fill down isn’t the absolute best on the market, it strikes a solid balance between quality and affordability. In fact, the Parsec’s slightly less-premium materials help keep its price under $500, making it a more budget-friendly alternative to sleeping bags from Sea to Summit, Feathered Friends, and Western Mountaineering, which range from $550 to $630. Plus, its 20-denier nylon shell is twice as thick as the fabric found on many ultralight competitors, meaning the Parsec is built to last if treated well. Unless you frequently camp in frosty conditions, most backpackers will sleep comfortably in this bag. For more, read our review of the Therm-a-Rest Parsec 20.
Six decades after it helped pioneer sleeping bag design in the U.S., Western Mountaineering’s standard is still hard to beat. The UltraLite is the brand’s flagship three-season model; while it remains a top pick, it’s pricier than other high-performing competitors.
Six decades after it helped pioneer sleeping bag design in the U.S., Western Mountaineering’s standard is still hard to beat. The UltraLite is the brand’s flagship three-season model; while it remains a top pick, it’s pricier than other high-performing competitors.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
25/14°F (ISO Comfort/Limit)
Other Temps
N/A
Weight
1 lb. 13 oz.
Fill
1 lb. of 850-fill down
Pros
Cons
Not many American outdoor brands have the trail cred of Western Mountaineering, which has been keeping backpackers warm since 1970. The UltraLite is the brand’s most popular three-season sleeping bag, and as with nearly every WM bag we've tested, there’s a lot to love. Its 12-denier nylon fabric feels soft against the skin, and the premium 850-fill-power down makes it highly packable without sacrificing warmth. With 1 pound of fill weight, the 20-degree temperature rating holds true—if anything, we’ve found that Western Mountaineering bags often run warmer than advertised. Its versatile rating makes it suitable for most three-season backpacking trips, and when paired with a liner and a warm sleeping pad, it can even handle mild winter conditions.
That said, Western Mountaineering may be resting on its laurels. While the UltraLite is a great bag, its design hasn’t been updated in a while, and competitors have caught up with warmer, lighter, and sometimes more affordable alternatives. Take the Feathered Friends Swallow UL, for example—a 20-degree powerhouse that features more water-resistant Pertex Endurance fabric, roomier dimensions, 950-fill-power down, and a lighter weight, all at the same price point (technically, one dollar less). Similarly, the Sea to Summit Spark 15 weighs less (1 lb. 9.7 oz.), costs less ($549), and is actually warmer thanks to nearly an extra ounce of 850-fill down.
To be clear, we’re still big fans of Western Mountaineering, and the UltraLite remains an excellent sleeping bag that will satisfy even the most discerning backpackers. But these days, there are other compelling three-season options worth considering.
The Down Hugger accommodates most sleep positions thanks to its ingeniously stretchy material, and it’s exceptionally light as well. Its main drawback is that it suffers from the typical ultralight durability pitfall.
The Down Hugger accommodates most sleep positions thanks to its ingeniously stretchy material, and it’s exceptionally light as well. Its main drawback is that it suffers from the typical ultralight durability pitfall.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
32/23°F (ISO Comfort/Limit)
Other Temps
-4, 9, 14, 30, 37, 45F
Weight
1 lb. 8.8 oz.
Fill
800-fill down
Pros
Cons
At first glance, the narrow, cigar-shaped Down Hugger might look like it would appeal only to relatively thin hikers who sleep ramrod-straight on their back. Don’t judge this sleeping bag by its cover, though: Montbell designed the Down Hugger with elastic material on the interior that grants it a level of mechanical stretch far above any other bag we tested. As a result, its 51-inch shoulder girth can expand to a superbly roomy 72 inches, while the knee area goes from 42 inches to 59 inches. The materials and design work well with any type of sleeper, even those with wide shoulders or who like to sleep on their side. The result is that the bag stretches as you move while still conforming to your body, offering the freedom of a roomier bag without the extra space and weight.
Another weapon in the Down Hugger’s arsenal is its baffle-less design, in which its 800-fill power down is secured by a network of internal polyester/nylon yarn rather than walled baffles. This allows the down to shift with your body as you spread out or curl up within the bag, helping to prevent cold spots. Add in the soft hand feel of the Down Hugger’s nylon taffeta shell and a chunky neck baffle, and you have a bag that provides a hearty amount of comfort—all while remaining a minimalist’s dream. At just over one-and-a-half pounds, this is the lightest bag we tested (although it’s less warm than the 1 lb. 9.7 oz. Sea to Summit Spark 15), making it a great option for backpackers trying to cut weight from their kits.
We’ve harped on this plenty, but it’s always worth mentioning that—as with most ultralight sleeping bags—the Down Hugger’s 10-denier nylon shell can be prone to insulation-leaking rips if you’re not careful. This bag is also about as minimalist as it gets, lacking a zippered stash pocket while sporting an average-size hood. But if you like the design, the good news is you have options: Montbell makes the Down Hugger in a plethora of temperature ratings, in addition to more thermally efficient 900-fill versions.
The Riff pairs nominally weight-saving materials with a comfort-minded mentality, but the results aren’t spectacular. This bag feels great, but we wish it leaned into either its roominess or packability even more.
The Riff pairs nominally weight-saving materials with a comfort-minded mentality, but the results aren’t spectacular. This bag feels great, but we wish it leaned into either its roominess or packability even more.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
28/17˚F (ISO Comfort/Limit)
Other Temps
30F
Weight
2 lb. 10 oz.
Fill
1 lb. 3 oz. of 800-fill down
Pros
Cons
The Riff is somewhat of a confusing backpacking sleeping bag. On one hand, it leans heavily into comfort—and does it well. Our tester, who used the Riff while traveling through Norway’s Lofoten Islands and backpacking in the Picos de Europa, praised its plush polyester material and cushy 800-fill-power down, which provided a fluffy, cozy feel that kept her warm throughout her trip. The bag is also loaded with features, including a pillow pocket to keep your head support in place, a foldable draft collar that mimics a blanket, and two vents on the chest for easy temperature regulation. If features are what you’re after, the Riff has them in spades.
However, the Nemo Riff 15 struggles with its identity. Despite its comfort-driven design, the shoulder (60 in.) and hip (53 in.) girths are actually narrower than many mummy bags—which is confusing, considering its hourglass shape expands at the knees (57 in.) to accommodate side sleepers. And while Nemo markets the Riff as its premier backpacking model, its feature-heavy design and hefty down fill (1 lb. 3 oz.) make it too heavy and bulky for serious backcountry use. The women’s version contains even more down to compensate for colder sleepers, pushing its weight past 3 pounds—a tough sell for a true backpacking setup.
That’s not to say the Riff is a total miss. Nemo’s top-tier construction is fully on display, and our tester found the bag to be durable and long-lasting. It’s also plenty comfortable for car camping, where we’d appreciate its design and materials more than if we were hauling it deep into the backcountry. (That said, we’d probably just opt for the Nemo Disco 15, which offers the same features, is roomier, and costs $100 less.) And at $400, while relatively affordable for a 15-degree bag, the Riff still isn’t cheap. Ultimately, we’d rather spend our money on a bag with a clearer use case. For more, read our review of the Nemo Riff 15.
The purpose-built Sidewinder is made for one specific group of backpackers: those who sleep almost exclusively on their sides. However, it’s not for everyone, and is middling in weight and packability.
The purpose-built Sidewinder is made for one specific group of backpackers: those who sleep almost exclusively on their sides. However, it’s not for everyone, and is middling in weight and packability.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
30/19°F (ISO Comfort/Limit)
Other Temps
35F
Weight
2 lb. 4 oz.
Fill
1 lb. 3 oz. of 650-fill down; synthetic
Pros
Cons
The Sidewinder SL doesn’t look like any other bag on this list, and it wears its specialization with pride. Big Agnes designed this bag so that its hood and zipper face the side (if you’re viewing the bag from above). When sleeping on your side—and if you purchased this bag, you should be—they face the “correct” direction (i.e., in front of you and out of your way). For side-sleepers who’ve long gotten tangled up in their bag’s hood or rested uncomfortably on top of a zipper, the Sidewinder represented a significant step forward when it hit the scene. It’s still one of our two top picks for sleeping in this position, although the Nemo Disco is also a good—and more versatile—option. (Check the “Versus” breakdown below for more.)
Unlike other bags with a reputation for being side-sleeper-friendly, the Sidewinder is pretty narrow. This mummy-shaped bag is especially tight through the legs, and its 31-inch footbox is among the smallest we tested. That might dissuade some campers, side-sleepers or not, although the Sidewinder does feature some smart design elsewhere. In addition to its 650-fill-power down insulation, it has synthetic fill at the hips and feet. Because you’ll most likely smoosh those areas while sleeping on your side, this helps retain warmth due to synthetic insulation’s trait of continuing to insulate when it’s compressed, unlike down.
Because of its uninspiring down fill power and synthetic portions, the Sidewinder isn’t the pick if you’re looking for a particularly lightweight or packable bag. But at less than two-and-a-half pounds, you can certainly take this bag into the backcountry (albeit probably not very deep), and its main calling card remains: An inventively designed bag that side-sleepers should consider. For more, read our review of the Sidewinder SL 20.
One of the least-expensive bags we tested, the Trestles Elite Eco achieves its value-buy status mostly due to its synthetic fill, which is less packable than down. While we’re big fans of its enormous extra-wide version, this bag doesn’t match its down competitors.
One of the least-expensive bags we tested, the Trestles Elite Eco achieves its value-buy status mostly due to its synthetic fill, which is less packable than down. While we’re big fans of its enormous extra-wide version, this bag doesn’t match its down competitors.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
24/12°F (ISO Comfort/Limit)
Other Temps
0, 30F
Weight
3 lb. 8.4 oz.
Fill
Synthetic
Pros
Cons
The Trestles Elite Eco is the only synthetic sleeping bag we tested, and while it has clear trade-offs compared to down, it also offers distinct advantages. First and foremost is water resistance—because synthetic insulation doesn’t lose loft when wet, it insulates even in damp conditions, whereas even DWR-treated down eventually fails when exposed to constant moisture. This makes the Trestles Elite Eco a solid choice if you expect wet weather but don’t want to invest in a premium down bag with a highly water-resistant shell. Another big plus? Price. Synthetic fill keeps costs low, making the Trestles Elite Eco one of the most budget-friendly options. If you want to build out your gear kit without breaking the bank, this and the down-filled Kelty Cosmic are good places to start.
However, synthetic insulation has a notable downside—it’s far less packable than down. While the Trestles Elite Eco 20 isn’t excessively heavy (2 lb. 6 oz.), it’s too bulky for serious backpacking. The included compression stuff sack helps, but it still can’t match a down bag in packability even at its most compact. Additionally, synthetic fill compresses permanently over time, meaning the Trestles Elite Eco won’t last as long as a high-quality down bag. That said, our tester found the bag’s soft material impressive during an overlanding trip through Eastern Washington, and she appreciated the dual zippers for easy entry and exit, plus the zippered stash pocket and anti-snag zipper design.
One unique perk of the Trestles Elite Eco is its extra-wide size option, which is the roomiest sleeping bag we tested. With a shoulder girth of 76.5 inches and a hip girth of 71.5 inches, it’s a dream for side sleepers or anyone who tosses and turns at night. However, all that space has a downside—our tester found that the larger interior took more heat to fill, leaving her cold on a 30-degree night. If you opt for the extra-wide version, make sure to bring extra layers to compensate for the space-for-warmth trade-off. For more, read our review of the Trestles Elite Eco 20.
The Spark is all about simple design and premium materials, and this light, warm mummy bag is packable enough for any backpacking trip. Some sleepers may find its lack of bells and whistles slightly disappointing for the high price.
Warmth / Weight
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Features
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Water Resistance
Sustainability
Despite its no-frills mummy design, there’s much to like about the reasonably priced Bishop Pass. It’s not supremely light or packable, but it’s a good value buy for hikers who sleep in relatively balmy three-season temps.
Warmth / Weight
Comfort
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Sustainability
It’s easy to love this bag’s impressive combination of warmth, low weight, roominess, and packability. The Swallow UL’s price tag isn’t for the budget-conscious, but for serious backpackers, it’s well worth the spend.
Warmth / Weight
Comfort
Features
Durability
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Sustainability
REI Co-op Radiant 20 ($199): New Budget Bag on the Block
Watch out, Kelty Cosmic—there’s a new contender in the budget down bag arena. The REI Co-op Radiant 20 costs just $19 more but delivers significantly more warmth, with 1 pound 9.4 ounces of 600-fill down compared to the Cosmic’s 1 pound 0.4 ounces of 550-fill. It also boasts the roomiest fit of any REI sleeping bag to date, making it a great pick for side sleepers (it comes in a generous nine sizes). Comfort-focused features like a snag-free zipper, draft collar and tube, and interior stash pocket round out the design. At 2 pounds 11 ounces for the medium, it’s one of the heavier bags on our list—but still an excellent value for budget-conscious backpackers who prioritize space and warmth.
Nemo Sonic 0 ($600): Cold-Weather Hero
Headed out for a winter backpacking trip? If temperatures are expected to dip well below 20°F, you’ll want something warmer than the three-season bags listed above. The Nemo Sonic 0 is a standout, packing in 1 pound 12 ounces of 800-fill down to create a cozy haven against the cold. It also includes thoughtful features like a waterproof/breathable footbox to combat tent condensation, stretch construction at the knees for comfortable side sleeping, and Nemo’s signature Thermo Gills, which let you vent heat on milder nights. At 3 pounds 4 ounces, it’s undeniably heavy—but that’s the tradeoff for true winter warmth. For a more budget-friendly option, consider the 0-degree Mountain Hardwear Bishop Pass ($355), but expect tradeoffs in packed size, roominess, and ventilation.
Our overall rating gives you the full scoop on a sleeping bag, factoring in price, build quality, performance (based on intended use), durability, and more. On the high end of the rating scale are standout sleeping bags with something special to offer, whether they’re the crème de la crème or budget designs that offer a savvy combination of features for the price. If you ask us, most readers should be looking to purchase a bag with an above-average overall rating—there’s simply little reason not to. That said, sleep sacks with lower overall ratings are still notable enough to have made our list; for various reasons, these might be compelling to users with specific design preferences or beginner backpackers who might also be using the bag for car camping.
The warmth-to-weight ratio balances two key factors in a sleeping bag: how much insulation it provides and how much it weighs. Since backpacking demands lightweight and efficient gear, this metric gives a clearer picture of real-world performance than looking at warmth and weight separately. Folks focused on keeping a low weight and minimal packed size (packability almost 100% correlates with weight in sleeping bags) should prioritize a competitive warmth-to-weight rating. On the other hand, comfort-focused backpackers, budget-conscious buyers, and those looking for a crossover bag for both camping and backpacking can often afford to compromise here in favor of a lower-cost or roomier option.
Excellent warmth-to-weight and warmth-to-packability ratio, thanks to high-fill-power down (800-fill and above) and thin shell, a streamlined silhouette, and minimal features. Ideal for serious adventurers looking to minimize weight and space.
Average warmth for the weight. Fill powers range from 550 to 850; higher fill-power bags will be fully featured, while the lower fill-power bags keep features to a minimum. Look for some semi-rectangular bags in this category, too.
Poor warmth for the weight due to low fill-power down or synthetic insulation, roomy dimensions, and lots of features.
Comfort plays a crucial role in determining how well you’ll sleep in a bag, right alongside warmth. This category includes a bag’s dimensions—roomier designs offer more freedom to move, while slim silhouettes can feel restrictive—as well as the softness of its fabrics. Quality-of-life features like draft collars (the puffier, the better), draft tubes, and vents also contribute to overall comfort, helping to regulate temperature throughout the night. While high-comfort bags tend to come with a weight penalty, they provide the most plush sleeping experience. On the other hand, backpackers focused on keeping their base weight low may be willing to sacrifice a bit of comfort for a more streamlined and lightweight setup. That said, after a long day on the trail, most sleeping bags will feel cozy enough.
Above-average comfort due to soft materials, lofty draft tubes and collars, and roomy dimensions. Many of these bags are built with side sleepers in mind.
The majority of mummy sleeping bags land here. These bags place function over comfort (including narrower dimensions and streamlined draft collars) but are still cozy enough for a good night’s sleep.
Synthetic sleeping bags that lack the cozy loft of down.
A sleeping bag’s features go beyond comfort—they also impact convenience, ease of use, and overall versatility. Some of the most common design elements include secure storage pockets (either inside or outside the bag), sleeping pad attachment straps, two-way zippers with anti-snag sliders, and ventilation options. The Therm-a-Rest Boost 650 stands out in this category with its unique armholes and center zip, which, when fully closed, boosts thermal efficiency by about 10 degrees. As with comfort, highly featured bags tend to be heavier and bulkier, but for those who enjoy fine-tuning their sleep system, this is a category worth paying attention to.
Expect a plethora of features, ranging from vents and arm holes to pillow pockets, zippered storage, two- (or three!) way zippers, draft collars, expanded foot pockets, and more.
Average feature set, generally including a draft collar and a small pocket.
Minimal feature set.
No sleeping bag is truly bombproof like a sturdy pair of hiking boots or a rugged backpack, but durability still matters—especially if you tend to be hard on your gear, plan to bivy under the stars, or want a bag that will last for years (or even generations). While most sleeping bags spend their lives safely inside a backpacking tent or stuff sack, exposure to rough ground, pets, or repeated compression can take a toll over time. A more durable bag often means a heavier and bulkier design, but for some, the trade-off is well worth it. Shell denier is the biggest factor in durability, though we also consider details like zippers (anti-snag sliders are a game-changer), stitching quality, and overall construction.
Shell fabrics from about 20-denier and higher, along with anti-snag zippers and reinforced fabric in high-use areas like the footbox.
Shell fabrics ranging from about 15 to 20-denier. Bags get a bump for anti-snag zippers and durable fabric blends like Pertex Endurance.
Shell fabric is 10-denier or thinner.
Even if you’re sleeping in a well-protected tent, moisture can still be a concern. Wet tent walls—whether from rain or condensation—are notorious for transferring moisture to sleeping bags, especially at the feet. A sleeping bag’s water resistance primarily depends on two factors: the shell fabric’s ability to repel moisture (typically via a durable water-repellent, or DWR, coating) and the insulation’s performance when wet. Hydrophobic down resists moisture better than untreated down but still loses loft when soaked, while synthetic insulation retains warmth even when damp, making it a safer bet in persistently wet conditions.
For those camping in dry climates or prioritizing warmth-to-weight efficiency, a down bag with a standard DWR finish should suffice. But if you often sleep in damp environments—think the Pacific Northwest, Appalachian backcountry, or alpine zones—it’s worth investing in a bag with added protection. Cold sleepers and winter campers should be especially mindful: wet insulation can turn a warm bag into a dangerously ineffective one, making water resistance an essential factor in extreme conditions.
Water-resistant shell and hydrophobic down or synthetic insulation offer best-in-class protection from light moisture. These bags get a slight bump for highly water resistant reinforcements at the hood and feet.
Water-resistant shell and hydrophobic down. Bags with non-treated down (like the Swallow) get a bump due to their extra water-resistant fabric.
Water-resistant shell; down is not treated with a durable water-repellant finish.
Our sustainability rating for sleeping bags takes into account ten different criteria. On the product level, we look for recycled or Bluesign-approved materials, responsibly sourced down, and PFAS/PFC-free durable water-repellent finishes. On the brand level, our criteria include whether the company offers repair services, has a dedicated resale or recycling program, uses recycled or reduced packaging, employs responsible manufacturing practices, monitors greenhouse gas emissions, and publishes an annual impact report. Sleeping bags with a high sustainability rating meet several of these criteria, while those with a lower rating may meet only a few—or none at all. We also consider the extent to which these criteria are met; for example, 10% recycled materials is not the same as 100% recycled materials. Additionally, not every sustainability effort by a brand or product fits neatly into our categories, so we may adjust ratings accordingly. You can find more details on these factors in the sustainability drop-down under each product above.
These sleeping bags are among the most sustainable on the market and earn our Better Trail Certified distinction. They often meet most of our sustainability criteria for this category.
These sleeping bags are a good, middle-of-the-pack option for sustainability. They often meet about half or more of our criteria for this category.
These sleeping bags are the least sustainable and have significant room for improvement. They usually only meet about a quarter or less of our criteria.
Down Insulation
Down is the most common insulating material in backpacking sleeping bags, prized for its excellent warmth-to-weight ratio and packability. Made from plumage (not feathers, as is often assumed) sourced from the underbelly of geese or ducks, down traps heat extremely well when fully lofted and compresses easily for storage. While down has some natural resistance to moisture, many sleeping bag manufacturers apply a durable water-repellent (DWR) treatment to enhance its ability to repel water. However, once down gets too wet, it loses its insulating power, making moisture management an important consideration for those camping in damp conditions.
There are two key measurements used to assess down insulation: fill power and fill weight. Fill power indicates how lofty—and therefore how insulating—the down is. Higher fill power (typically 800 to 950 in premium sleeping bags) means the down is exceptionally lofty, providing excellent warmth while remaining highly compressible. Lower fill-power down (budget-friendly models often use 650) is less efficient, meaning it requires more down to achieve the same warmth, resulting in a heavier and bulkier sleeping bag overall.
While fill power indicates a sleeping bag’s quality and thermal efficiency, it doesn’t tell you how warm the bag actually is. For that, you need to consider fill weight—the total amount of down inside the bag. Take the Western Mountaineering UltraLite and the REI Co-op Magma 30, for example. Both use high-quality 850-fill down, but the UltraLite packs a full pound (16 oz.) of insulation, while the Magma has just 12.7 ounces. It doesn’t take a mathematician to figure out which bag is warmer. On the other hand, Kelty’s Cosmic Down 20 features just over a pound of 550-fill down, which provides significantly less warmth than the UltraLite’s 1 pound of 850-fill. Comparing bags with different fill powers can be tricky, but a little educated guesswork goes a long way.
For more on this topic, see our article Knowledge is (Fill) Power: How to Interpret Sleeping Bag Warmth and Weight.
Synthetic Insulation
Synthetic insulation is a man-made alternative to down, typically made from polyester. It’s designed to trap warmth in a similar way to down, but is no substitute for the real thing: It doesn’t loft or compress as well, resulting in a lower warmth-to-weight ratio. This makes synthetic bags bulkier and heavier than their down counterparts, but also more affordable—hence their popularity in budget-friendly sleeping bags. The Marmot Trestles Elite Eco 20 is a case in point here: it costs just $169, but weighs a whopping 3 pounds 8.4 ounces. Synthetic insulation is subjected to the same ISO testing as down, meaning a synthetic bag with an equivalent temperature rating will provide just as much warmth.
The biggest advantage of synthetic insulation is its ability to retain warmth even when wet. Unlike down—which, even with a DWR treatment, loses loft and insulating power when saturated—synthetic fibers resist compression when damp, allowing them to continue trapping heat. This makes synthetic bags a reliable choice for wet environments, provided you don’t mind the added bulk and weight. However, synthetic insulation breaks down faster than down, gradually losing its loft and warmth over time. So while a high-quality down bag can last for decades with proper care, a synthetic bag is unlikely to become a generational hand-me-down.
The shell (outer fabric) and interior lining of a sleeping bag are typically made from nylon or polyester. Nylon is slightly more durable for its weight, while polyester offers a bit more water resistance. Regardless of the material, sleeping bag fabrics are generally quite thin—manufacturers prioritize lightness and packability—so they require some care to avoid holes and tears. Ultralight sleeping bags often feature a 10-denier (D) shell, while more durable models may have 20D or even 30D materials for added toughness. Inside the bag, the lining is usually made of brushed nylon or polyester taffeta, which provides a softer, more comfortable feel against the skin compared to the shell fabric.
Most sleeping bag shells are treated with durable water repellent (DWR) to help shed moisture, but frequent use can cause this coating to wear off. If you regularly deal with wet tent walls or sleep under the stars, we recommend reapplying a DWR spray to maintain water resistance. For harsh-weather expeditions, some sleeping bags feature highly water-resistant materials like Pertex Quantum Pro or Gore-Tex Infinium, offering longer-term protection against moisture.
Both down and synthetic sleeping bags come in a variety of shapes, each with their own advantages and disadvantages. Here are the most common styles you’ll see on the market.
Mummy
Mummy bags are prized for their warmth-to-weight ratio, packability, and thermal efficiency. They’re generally slimmer than semi-rectangular or rectangular bags, tapering significantly from the torso through the legs and footbox. This form-fitting shape not only reduces material bulk but also excels at trapping heat. Their minimalist design makes mummy bags the lightest and most compressible option for weight-conscious backpackers, especially when filled with premium down (800 fill power and above). As a result, the highest-performance bags on our list—like the Feathered Friends Swallow UL 20 and the Sea to Summit Spark 15—are mummy-style. That said, their snug fit may feel restrictive for larger campers or those who toss and turn at night.
Semi-Rectangular
Arguably the most versatile sleeping bag shape, semi-rectangular models strike a balance between the thermal efficiency of a mummy bag and the spaciousness of a rectangular design. With a much gentler taper, they offer more room through the legs and footbox while still maintaining decent heat retention. This category encompasses a wide range of designs—Nemo’s “spoon-shaped” Disco and Riff, for example, provide extra space at the shoulders and hips while staying slimmer elsewhere (for more, read our Nemo Disco 30 review and Nemo Riff 15 review). For hikers who want a packable bag without feeling confined, semi-rectangular options offer a comfortable middle ground.
Rectangular
Rectangular sleeping bags are rare in the backpacking world since their spacious design prioritizes comfort over weight and packability. (Many backpackers who like to sprawl out opt for a roomy semi-rectangular bag or a down quilt instead.) That said, if you’re not covering long distances or don’t mind carrying the extra bulk, a rectangular bag offers a sleep experience that’s about as close as you’ll get to your bed at home—making them a great choice for car camping. However, with all that extra space comes a trade-off: these bags take longer to warm up and can feel chilly for smaller sleepers.
Like a jacket hood, a sleeping bag’s hood fits over your head (and sometimes your camp pillow) to keep you warm through the night. It’s insulated just like the rest of the bag, helping to trap heat where it’s most needed. Hoods range from snug, minimalist designs on mummy bags to generously padded, oversized versions on warmer or roomier models. Most feature a cinchable cord-and-toggle system for a customizable fit, while some also include hook-and-loop tabs or buttons for added security.
A draft collar is an insulated baffle sewn into the inside of a sleeping bag around the neck area, designed to seal in warmth and keep cold air from creeping in. Cinch it snug, and you’ll stay draft-free from the neck down without needing to cover your face and restrict breathing. This plush barrier is one of the coziest and most effective features for improving thermal efficiency. Sleeping bags rated for 20 degrees and below typically include a draft collar, while warmer-weather bags may forgo it. Many cold-weather bags also feature a draft tube—a long, insulated strip along the main zipper—to further prevent heat loss.
Baffles are the compartments in down sleeping bags that keep the insulation evenly distributed, preventing clumping and cold spots. They come in various shapes and orientations—horizontal, vertical, or even a less common boxed pattern. Some sleeping bags feature open channels (also known as “continuous baffles”) that allow users to adjust the down placement, seen on designs like the Feathered Friends Swallow UL 20 and Western Mountaineering UltraLite. However, we’re cautious about the continuous-baffle design for all but the most experienced users, as down can migrate and create cold spots if not carefully managed.
The two primary types of baffle construction are box baffles and sewn-through construction. Sewn-through baffles are exactly as they sound—the stitching runs straight from the outer shell to the inner lining. This design is lighter and more affordable but creates weak points at the seams where insulation is absent, allowing cold air to seep in. Box baffles, on the other hand, use strips of fabric to create enclosed compartments between the shell and liner, effectively eliminating cold spots and improving warmth retention. Sea to Summit’s Spark sleeping bag line showcases both constructions in action: the Spark 45 features sewn-through baffles for a lighter weight, the Spark 30 uses box baffles in the torso with sewn-through construction below the waist, and the Spark 15 is fully box-baffled for maximum warmth.
A sleeping bag’s footbox is located at the toe end and—unsurprisingly—is the space where your feet rest when you’re lying down. In many sleeping bag designs, the footbox is more than just the “end” of the bag, though. Manufacturers frequently overstuff the footbox baffles to maximize heat (feet tend to get cold faster than the rest of the body) or give them some structure to create more room for those who sleep on their backs. The Therm-a-Rest Parsec even features a “Toe-asis” foot pocket that gives you a sleeve to cozy up your feet on a cold night.
More than just an entry and exit point, a sleeping bag’s zipper can add versatility and comfort. Many models feature two-way zippers, allowing you to vent the bottom of the bag for airflow on warm nights. Some bags have zippers on both sides, creating a blanket-like design that lets you fold the top half up or down as needed. Others include auxiliary zippers—like the Therm-a-Rest Boost’s WarmZip—which expand or contract the bag’s width for a customizable balance of space and thermal efficiency (read our Boost 650 20 review). And for those who like to share the warmth, some manufacturers even design their zippers to be linked together, turning two sleeping bags into one cozy backcountry cocoon.
It’s not super common, but some sleeping bags feature small vents—usually on the torso—that you can open or close with a zipper to release heat. These vents may be backed by fabric (as in the case of the ThermoGill vents on the Nemo Disco 30) or they might go straight through, allowing you to use them as armholes too. In general, we think that vents (and armholes) are a fairly superfluous feature, but if you sleep warm or love the idea of performing camp chores or reading a book while “wearing” your sleeping bag, they could be a fun addition.
Many modern sleeping bags include small pockets on the interior or exterior, offering convenient storage for essentials. For instance, the Therm-a-Rest Parsec 20 features a zip pocket on the outside near the neck, while the REI Co-op Magma 30 has an interior sleeve, which feels more basic but still useful. These pockets are perfect for storing items like your phone (keeping it warm in cold environments), earplugs, or other small essentials you want to keep within easy reach while in your tent.
Sliding off your sleeping pad in the middle of the night can be frustrating, which is why some sleeping bags include fabric loops or attachment systems to keep you securely in place. These designs vary from manufacturer-specific systems that pair with certain pads to universal loops that accommodate almost any mat. A great example is the Therm-a-Rest Parsec 20, which features removable straps (dubbed “SynergyLink Connectors”) that can be added or taken off depending on your needs (read our review of the Therm-a-Rest Parsec 20).
Every sleeping bag comes with a stuff sack, which allows you to store it in a compressed state while hiking. However, not all stuff sacks are created equal—some use higher-quality materials or have more user-friendly designs. The best options include compression straps, enabling you to pack the sleeping bag down to its smallest possible size. If your bag doesn’t come with a compression sack but you want to save backpack space, you can always purchase one separately.
Keeping a sleeping bag in its stuff sack for long periods can compress the insulation—whether down or synthetic—leading to loss of loft and reduced warmth over time. To prevent this, most sleeping bags come with a large storage sack, which protects the bag while allowing it to rest in a lofted state. For long-term storage and to extend the lifespan of your bag, we recommend always keeping it in its storage sack or a similarly sized container.
Sleeping bags are typically sold in regular and long sizes, with manufacturers listing the exact lengths on product pages. A regular size is usually 72 inches (6 ft.), while long versions extend to 78 inches (6 ft. 6 in.)—though these measurements can vary by brand. Some models also come in short (66 in.) or women’s-specific versions, which are generally shorter in length and wider at the hips to better fit the average female silhouette.
Choosing the right length is straightforward:
Most sleeping bags come in a single width, but there are ways to ensure a good fit. Mummy bags tend to be the slimmest, while semi-rectangular models like the Nemo Disco 30 or Therm-a-Rest Boost 650 20 provide more room to move. To make an informed choice, check the manufacturer-listed shoulder, hip, and footbox girths, which indicate the bag’s internal circumference at those points. For example, a bag with a 64-inch shoulder girth will feel noticeably roomier than one with a 60-inch girth.
Some brands, like REI, offer multiple width options—its Magma mummy bag comes in Narrow, Standard, and Wide, giving you even more customization. While width is largely a matter of personal preference, it’s especially important if you have a larger frame, broad shoulders, or simply prefer extra room. Just keep in mind that narrower bags retain heat more efficiently and are lighter and more packable than roomier alternatives.
To choose the right sleeping bag warmth rating, consider the typical nighttime temperatures where you backpack most often. Below is a breakdown of temperature ranges and their ideal use cases:
Additionally, know your personal sleep habits—do you sleep warm or cold? If you tend to sleep cold, consider going one warmth level higher than the temps suggest. If you sleep warm, you may get away with a lighter bag.
Among all the sleeping bag specs, temperature ratings—also known as ISO ratings (formerly EN ratings)—are the most important. These standardized ratings indicate how warm a sleeping bag is and the environments it's best suited for. While individual warmth preferences vary, the ISO testing standardizes comparisons across brands, meaning a 15°F-rated bag from Therm-a-Rest should, in theory, be just as warm as a 15°F-rated bag from Nemo (though real-world performance can differ, and we note when it does).
After undergoing ISO testing, each sleeping bag is assigned three temperature ratings:
It’s important to note that these ratings are for “average” cold and warm sleepers; since everyone sleeps differently, your ideal bag may differ from the ISO rating. Additionally, these tests assume the sleeper is wearing midweight baselayers, so your clothing (or lack thereof) will impact warmth.
Unfortunately, there’s no industry-wide standard for what temperature appears alongside the bag's name. The closest "standard" we have is that women's bags often advertise their comfort rating, while men's use the lower limit (for more on this, see our question below on men's vs. women's bags). The REI Co-op Magma 15, on the other hand, is named for a temp that falls between its 21-degree comfort rating and 9-degree lower limit. The moral of the story? Always check the actual tested temperature ratings before buying and don’t simply rely on the name.
Choosing a sleeping bag shape depends on more than just your height and body type—it also comes down to how you sleep and whether you prioritize weight and packability. Side-sleepers and those who move around at night will likely prefer a semi-rectangular bag or a mummy-adjacent design, such as Nemo’s hourglass-shaped Riff 15, which provides more room to shift positions while still being relatively lightweight and packable. If you don’t mind a snug fit and want to maximize warmth while minimizing bulk, a mummy bag like the Feathered Friends Swallow UL 20 is the most efficient choice for backpackers looking to keep their pack weight low without sacrificing insulation. It’s worth noting that Feathered Friends also offers the Hummingbird and Swift series, which feature the same design as the Swallow but in a narrower and wider silhouette, respectively.
Finally, if comfort and space are your top priorities, a rectangular or extra-roomy semi-rectangular bag will let you stretch out freely, making them a great option for car camping—though their bulkier design is generally impractical for backpacking.
The biggest factor in sleeping bag price is materials, which directly impact warmth, weight, and packability. High-end sleeping bags typically use ultra-lofty, super-packable down, often starting at 800-fill power and reaching 900-fill power or more (such as the 950-fill Feathered Friends Swallow UL 20). These premium bags are incredibly thermally efficient, meaning they provide maximum warmth for minimal weight, making them a great choice for backpackers who prioritize low pack size and weight. However, this level of performance comes at a cost—$600 or more in many cases.
Cheaper sleeping bags, on the other hand, tend to be heavier, bulkier, and more budget-friendly. The good news is that a lower-priced sleeping bag with an ISO Comfort Rating of 20 degrees will still keep you just as warm as a high-end 20-degree bag. However, budget bags often lack the soft, lofty feel of premium down and can take up significant pack space—sometimes filling the entire bottom of a backpack. Synthetic sleeping bags also fall into this category, offering affordability and wet-weather performance but at the cost of extra bulk and a shorter lifespan, as synthetic insulation tends to compress and lose loft over time.
In the end, if your main goal is simply to stay warm and comfortable, you can achieve that with both budget and premium bags. But if you’re a serious backpacker tackling multi-day trips, investing in a lightweight, high-quality bag can make a big difference in comfort, efficiency, and enjoyment on the trail.
First off, treat your sleeping bag with care when you’re in the field. The thin shell fabric can rip easily, and losing down through a hole will make your bag colder. If you’re using it outside the tent, be mindful of where you’re sitting or lying down, and avoid sharp objects while inside to prevent accidental damage.
Once home, make sure to air out your sleeping bag after you return from a trip, as this releases any trapped moisture. Never store it in its stuff sack, as prolonged compression can damage the insulation’s loft. Instead, use the larger storage sack that comes with most bags and keep it in a cool, dry place, like a closet.
If your bag gets dirty, you can spot clean it as needed with a non-abrasive soap. For a full wash—recommended about once per season—use a detergent made for down or synthetic insulation, depending on your bag’s fill. Nikwax’s Down Wash Direct is an easy go-to. Wash your bag in a front-loading machine on a gentle cycle to avoid damaging the insulation or shell fabric. To dry, put your dryer on low heat and add a few tennis balls to help evenly redistribute and fluff up the insulation (especially important for down bags). Repeat as needed, or hang dry if your dryer isn’t large enough. Taking the time to care for your bag properly will help maintain its warmth and longevity for years to come.
The vast majority of sleeping bags are not waterproof, though many have a DWR (durable water-repellent) finish on the shell to help shed light moisture. Additionally, down feathers have some natural water resistance, and most manufacturers treat them with DWR to improve their ability to stay dry. However, if exposed to too much sustained moisture, down loses its loft and becomes ineffective at insulating. In wet conditions, a synthetic sleeping bag is often the better choice, as it retains warmth even when damp.
Some high-end sleeping bags feature highly water-resistant—or even waterproof—shells, but these models are typically expensive and designed for harsh, wet environments or expedition use. For most backpackers, using a waterproof/breathable bivy sack or a well-ventilated backpacking tent is the best way to protect against moisture. And emphasis here on breathable and ventilated—we had a sleeping bag fully soak through due to condensation inside an emergency bivy sack, rendering us just as cold—if not moreso—than we would have been if we’d opted to just sleep uncovered.
Side sleepers should look for a roomier sleeping bag with extra space in the hips and knees, allowing for movement without feeling restricted. One of the best options is the Nemo Disco, which features an hourglass shape that provides plenty of space for tucking your legs up comfortably. The Therm-a-Rest Boost 650 is another favorite and has a semi-rectangular shape that offers uninhibited freedom of movement throughout the night.
Another great choice is the Big Agnes Sidewinder SL, designed specifically for side sleepers. It has a side-facing hood, so you won’t end up breathing into it when you turn on your side. Additionally, its zipper placement stays in front, preventing it from shifting underneath you like a standard mummy bag might. All of these models cater to side sleepers by offering greater mobility and comfort compared to traditional, snug-fitting mummy bags.
Broadly speaking, sleeping bags are characterized by a main zipper that secures the bag around the body, enclosing you on all sides up to the neck. Quilts, on the other hand, have an open back—and often an open footbox, too. To use a quilt properly, you drape it over your body, tuck your feet into the footbox (if open, it can be cinched closed), and secure the quilt around your sleeping pad with included straps. While this may sound less secure than a sleeping bag, in practice it’s surprisingly effective at blocking drafts.
The idea behind quilts is that the insulation on the bottom of a sleeping bag is wasted since it gets compressed under your body, reducing its ability to trap heat. By eliminating this unnecessary insulation, quilts provide similar warmth at a lower weight. Because of this, they offer great appeal to ultralight backpackers and thru-hikers looking to shave weight from their base kit. Additionally, they have a wider temperature range than sleeping bags—a 20-degree quilt remains useful in summer conditions, as you can simply drape it over yourself and leave the footbox open for ventilation. However, sleeping bags still provide better all-around warmth in colder and windier conditions, making them the better choice for cold-weather backpacking or mountaineering.
Some sleeping bags come in men’s and women’s versions (like the Nemo Disco), while others are unisex (such as REI’s Magma collection, which offers nine size options). We like what REI has done here—rather than designing separate men's and women's bags, they focus on providing different lengths and widths, which ultimately matter more for finding the right fit. If you’re looking for a sleeping bag, pay attention to its dimensions first and foremost.
That said, there is one key difference between men’s and women’s sleeping bags worth knowing: temperature ratings. Most women’s sleeping bags are rated using the ISO Comfort Rating, which indicates the lowest temperature at which a cold sleeper will remain comfortable. In contrast, men’s sleeping bags often use the ISO Limit Rating, which represents the lowest temperature at which a warm sleeper can still sleep comfortably. This means that a women’s 20-degree bag is often warmer than a men’s 20-degree bag, even if both claim the same rating.
For example, take the Nemo Disco 15: The men’s version has 1 pound 7 ounces of 650-fill down and an comfort rating of 27°F, while the women’s version has 2 pounds (9 oz. more!) of 650-fill down and a comfort rating of 17°F. Thus, if you want more warmth for the price and don’t mind carrying a little extra weight and bulk, a women’s sleeping bag can be a sneaky way to get a better deal on insulation.
First off, what exactly makes a sleeping bag "sustainable"? Simply put, a sustainable sleeping bag is constructed in such a way that minimizes negative impacts on people and the planet. Key factors include using recycled materials, PFAS-free durable water-repellent finishes, and responsibly sourced down, and adopting brand-wide practices such as recycled or reduced packaging, repair services, and carbon footprint tracking.
When it comes to sustainable sleeping bags, Nemo and REI Co-op rise to the top. REI’s Magma leads the pack, earning an impressive 4.9 out of 5 in our sustainability ratings, thanks to its use of Bluesign-approved materials and REI’s commitment to ethical sourcing. Close behind are Nemo’s Disco and Riff bags, which score a solid 4.5. Their biggest drawback is the absence of Bluesign-certified materials and Nemo’s lack of participation in third-party programs like Fair Trade or Fair Wear, which independently verify factory working conditions and environmental impact. That said, Nemo does publish a code of conduct aligned with International Labor Organization standards. Meanwhile, REI loses a few points for not offering an in-house repair program, which could extend the life of their gear and reduce waste.
It's also worth highlighting Nemo’s Endless Promise, an end-of-life recycling initiative that ensures the Nemo Disco and Riff sleeping bags are fully recyclable. Through this program, you can send your bag back to Nemo when it's no longer usable, and they'll carefully disassemble it and recycle each component separately. It’s a cool initiative, but we're not sure we'd ever use it—a high-quality sleeping bag should last long enough to pass down to the next generation. In that spirit, we genuinely hope the Endless Promise program will still be available when our kids—or even their kids—finally decide it's time to recycle our well-loved Nemo sleeping bag. For more information, you can check out our Nemo Disco Sustainability Report.
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