Cozying into your sleeping bag at the end of a long day on the trail is one of the great pleasures of backpacking. And today’s bags offer exceptional warmth for the weight along with a range of technologies that help them stay dry and perform in a variety of conditions. The majority of the bags on this list are filled with down, which is warmer, lighter, and more compressible than synthetic insulation, although we did include a handful of top synthetic models as well. For more background information, see our sleeping bag comparison table and buying advice below the picks.
Temperature rating: 20˚F
Weight: 1 lb. 10 oz.
Fill: 14 oz. of 900-fill down
What we like: Premium down and build quality for serious backpackers.
What we don’t: Pricey and availability can be limited during peak season.
For the best combination of comfort, quality, and warmth-to-weight, it’s hard to beat a Feathered Friends sleeping bag. This boutique Seattle-based brand specializes in premium down products and makes just about everything in the Pacific Northwest. Climbers stop in religiously before heading to Mt. Rainier, Alaska, and far-off places like the Himalaya, and it’s well worth a visit if you’re in Seattle (their store is right across from the REI flagship). And with a direct-to-consumer model, Feathered Friends sleeping bags and other down products are exceptionally well-made and competitively priced for what you get.
For 3-season use, the Hummingbird YF is our favorite sleeping bag on the market. It’s stuffed with a generous 14 ounces of 900-fill goose down, has a water-resistant 20-denier Pertex Quantum shell, and comes in at a reasonable 1 pound 10 ounces for the 20-degree model (in our experience, Feathered Friends bags run warmer than their listed ratings). And while $449 is a significant investment, the Hummingbird is built to last: after almost a decade of use, our bag shows little sign of wear and is as warm as the day we bought it. Further, held up against the popular Western Mountaineering UltraLite below (also rated to 20˚F), it’s slightly lighter and significantly cheaper. For those who want to cut even more weight, Feathered Friends also makes the Hummingbird UL (1 lb. 8 oz.) with a thinner 10-denier shell and more premium 950-fill down for $539.
See the Feathered Friends Hummingbird YF See the Women's FF Egret YF
Most Comfortable Sleeping Bag for Side Sleepers
Temperature rating: 25°F ISO Comfort, 14°F Lower Limit
Weight: 2 lbs. 11 oz.
Fill: 22 oz. of 650-fill down
What we like: A roomy and comfortable sleeping bag for those who toss and turn.
What we don’t: Heavier and bulkier than slimmer-cut bags with similar temperature ratings.
Nemo does things a little differently with their sleeping bags, and they are a big hit among comfort seekers and side sleepers. Unlike slender mummy designs that trim dimensions to shave weight, Nemo utilizes a "spoon”-shaped concept on the Disco. The focus is on comfort: the bag is wider than a typical mummy, particularly in the elbows and knees, so side sleepers and others can roll around without feeling constrained. The Disco uses 650-fill, PFC-free hydrophobic down, a waterproof panel around the toe box for added protection, and a built-in sleeve for a pillow. For ventilation, you get two zippered “gills” running lengthwise at the top of the bag, and unzipping them creates intentional cold spots to release hot air in warm conditions. In use, we have found the system to be very helpful on mild nights.
The biggest downsides of the Nemo Disco are weight and bulk. First, the spacious design that results in the extra roominess means more fabric and down fill are required. At 2 pounds 11 ounces for the regular size, the Disco 15 is far from ultralight. Second, it doesn’t help that Nemo uses 650-fill down for this bag, which is decidedly mid-range (check out the 800-fill Riff 15 for a lighter but pricier alternative). That said, if the roomy fit and unique feature set appeal to you, the Disco 15 is a great option. And for a cozy synthetic bag from Nemo for $100 less, see the Forte 35 below.
See the Nemo Disco 15 See the Women's Nemo Disco 15
Best Ultralight Sleeping Bag for Backpacking
Temperature rating: 36°F
Weight: 14.3 oz.
Fill: 7.7 oz. of 850-fill down
What we like: An ultralight sleeping bag with fully baffled construction.
What we don’t: Fragile materials and limited warmth.
Feathered Friends sets the gold standard for premium down products, but Western Mountaineering is hot on their heels. Specializing in down sleeping bags, this San Jose-based company has a complete collection for every sort of adventurer, ranging from durable and waterproof expedition bags to featherweight quilts. The Flylite here is their premium ultralight offering for thru-hikers, fastpackers, and weight-conscious climbers, clocking in at just 14.3 ounces with over half its weight devoted to down fill (7.7 oz.). And it’s not just light: featuring highly compressible 850-fill down, a 10-denier shell and lining, and half-length #3 YKK zipper, the Flylite packs down to the size of a 1-liter Nalgene.
What sets the Flylite apart is its fully baffled construction, which eliminates cold spots found in sewn-through designs (a common weight-saving feature in UL bags, including the Sea to Summit Spark below). Using tiny baffles, Western Mountaineering is able to offer enhanced insulation without a significant weight penalty, resulting in what they claim to be the lightest fully baffled sleeping bag yet. It’s true that the Flylite is fairly limited to summer use (36˚F is the lower limit) and you’ll have to exercise a lot of care with the fragile zipper and fabric, but backpackers will be hard-pressed to find better warmth for the weight. For a slightly more affordable choice, it’s also worth checking out Western Mountaineering’s popular HighLite ($380), a 16-ounce design that features a combination of sewn-through and baffled construction.
See the Western Mountaineering Flylite
Best Budget Down Sleeping Bag
Temperature rating: 33°F ISO Comfort, 21°F Lower Limit
Weight: 2 lbs. 10 oz.
Fill: 16.4 oz. of 550-fill down
What we like: Inexpensive for a warm and well-made down sleeping bag.
What we don’t: Decently heavy and not nearly as packable as more premium models.
For new backpackers and those on a budget, Kelty makes inexpensive gear that may pleasantly surprise you with its quality. The Cosmic 20 is one of the cheaper down sleeping bags on the market—definitely from a major manufacturer—but the ISO Comfort rating of 33 degrees Fahrenheit should keep you cozy in most 3-season conditions. It’s worth noting that Kelty updated the Cosmic line for 2021, with the major change being slightly lower-fill-power down (550 instead of 600), along with a considerably cheaper price tag at just $140. At under 3 pounds for the regular version, it’s our favorite budget down bag for 2021.
Keep in mind that due to the lower fill-power down, the Kelty Cosmic is not nearly as light or packable as the more premium options on this list. By spending up, the Feathered Friends Hummingbird above offers approximately the same level of warmth for noticeably less weight, but it also happens to be over three times the price and more fragile. For those keeping an eye on their wallet and not counting ounces, it's hard to beat the value of this Kelty line, which also is offered in 40-degree and 0-degree versions.
See the Kelty Cosmic 20 See the Women's Kelty Cosmic 20
Best Sleeping Quilt for Backpacking
Temperature rating: 30˚F (also available in 0, 10, 20, 40, and 50˚ versions)
Weight: 1 lb. 1.9 oz.
Fill: 12.4 oz. of 850-fill down
What we like: Super customizable and great warmth for weight.
What we don’t: There's a wait time for custom models.
Some ultralighters and thru-hikers opt for a sleeping quilt, which have an open-back design that wraps around your sleeping pad and therefore cuts even more weight. And quilts are the bread and butter of Minnesota-based Enlightened Equipment, so it’s no surprise to see their Enigma at the top of our list for 2021. It packs a serious punch with a whopping 12.4 ounces of down, which is all concentrated along the front and side of the body. Further, Enlightened Equipment quilts are handmade and can be customized into a wide variety of sizes (16 combinations of length and circumference), plus you have the option of 850- or 950-fill down along with a whole range of temperature ratings. Priced at a reasonable $290 for the 30-degree model, the Enigma is our top choice for a sleeping quilt.
We’re big fans of sleeping quilts for their versatility and weight savings, but they’re not the ideal pick for every backpacker. The backless design makes it hard to fully batten down the hatches in cold weather, and with no hood you’ll want to be sure to pack additional coverage for your head (a beanie or hooded down jacket will do). Added up, we’d hesitate to take the Enigma into true winter conditions, although we certainly know those who do (it’s offered in a 0˚F version). Finally, as is the case with most cottage-industry brands, be sure to factor in a wait time: Most Enlightened Equipment products are made to order, which is great for customization, but products from larger companies often are available quicker.
See the Enlightened Equipment Enigma Quilt
Best of the Rest
Temperature rating: 28°F ISO Comfort, 16°F Lower Limit
Weight: 1 lb. 12.2 oz.
Fill: 15.9 oz. of 850-fill down
What we like: A lightweight sleeping bag for less than the competition.
What we don’t: From our experience, the Magma line doesn’t run quite as warm as suggested.
REI Co-op’s in-house offerings have been impressive of late, with a strong lineup of quality backpacking gear at competitive price points. The latest Magma 15 is case in point: for $389, you get a premium and warm backpacking bag that is loaded with 15.9 ounces of 850-fill down (REI also makes a 30-degree variation for $339). On paper, it’s right in line with top-tier brands but with less damage to your wallet (competing models from Feathered Friends and Western Mountaineering cost $449 and $525, respectively). The Magma isn’t cheap by any means—down is the most expensive insulator and for good reason—but it’s a solid value nevertheless, and especially with a member coupon.
But in practice, the REI Magma 15 has some shortcomings. Despite the impressive temperature rating, we’ve found that the bag doesn’t run quite as warm as suggested (that’s one of the reasons we included the 15-degree version here instead of the 30). It’s difficult to pinpoint exactly why, but the variable baffle spacing could have something to do with it—the baffles on the lower half of the body are noticeably wider than the upper half, which may be what left our legs and feet feeling a tad chilly. In addition, the shell can’t match the ultra-high-end feel of bags from Feathered Friends and Western Mountaineering. But you’d be hard-pressed to find a better value for the weight and warmth, earning the Magma a spot toward the top of our list.
See the REI Co-op Magma 15 See the Women's REI Co-op Magma 15
Temperature rating: 20°F
Weight: 1 lb. 2.6 oz.
Fill: 12.6 oz. of 950-fill down
What we like: Hoodless design hits the sweet spot of weight and performance.
What we don’t: No zipper and very thin fabrics.
The ultralight sleeping bag world is chock full of models that trim weight with premium down, ultra-thin shell materials, streamlined feature sets, and narrow dimensions. The Flylite gets our top pick for its fairly uncompromised design, but the hoodless Feathered Friends Tanager is an intriguing alternative. With no zipper or hood, this dedicated ultralight build saves weight on features but doesn't sacrifice on insulation with premium 950-fill down. The result is impressive to say the least: the 20-degree Tanager weighs just 1 pound 2.6 ounces total but contains a whopping 12.6 ounces of insulation. Do the math—you get 4.9 ounces more down in a 4.3-ounce heavier build—and it’s even warmer for the weight than the Flylite above.
There are a few reasons the Tanager doesn’t get our top UL pick, including the zipperless design, lack of hood, and ultra-thin fabric (you can literally see through the 7D x 5D Pertex Quantum shell). What’s more, the majority of thru-hikers and fastpackers won’t be venturing into sub-freezing temperatures, making the Tanager’s warmth a bit overkill for most conditions (it doesn’t help that you can’t zip open the bag for ventilation). But 3-season alpine climbers will find a lot to like from this purpose-built bag, and these compromises are well worth it for the weight savings. And for a full mummy design from Feathered Friends with a zipper, our top-ranked Hummingbird also comes in a UL version ($539), which features 14 ounces of down in a 1-pound 8-ounce build... Read in-depth review
See the Feathered Friends Tanager 20 CFL
Temperature rating: 26°F ISO Comfort
Weight: 2 lbs. 5.4 oz.
Fill: 650-fill down
What we like: A bit warmer and lighter than the Marmot Sawtooth below.
What we don’t: Tapered cut is not ideal for those who toss and turn.
There are a whole lot of very expensive sleeping bags on the market that use 800-fill-power down or even higher, and there a number of budget-oriented synthetic options, but the mid-range down offerings are surprisingly limited. In this category, we like the Mountain Hardwear Bishop Pass, which does a nice job putting it all together at a reasonable price. You get a cozy 26-degree ISO Comfort rating at 2 pounds 5.4 ounces total, making it slightly warmer and lighter than the Marmot Sawtooth below. And this bag is both well-built and comfortable, more so than the cheaper down bags on this list. At about half the price of a high-end model like the Feathered Friends Hummingbird YF, we like the value of the Bishop Pass.
Keep in mind that the Mountain Hardwear Bishop Pass manages to keep weight low by tailoring the cut of the bag. The regular size is 53 inches in terms of the hip measurement, whereas the Marmot Sawtooth and Kelty Cosmic are roomier at 57 and 58 inches, respectively. If you are a side sleeper who tosses and turns throughout the night, we recommend choosing one of the aforementioned options (or Nemo makes the roomiest bags out there). But for those who don’t mind a trimmer mummy cut, the Bishop Pass is a quality mid-range bag at a good price.
See the Mountain Hardwear Bishop Pass 15 See the Women's MH Bishop Pass 15
Temperature rating: 20°F
Weight: 1 lb. 13 oz.
Fill: 16 oz. of 850-fill down
What we like: Lightweight, super comfortable, and well-built.
What we don’t: Pricier and heavier than the Feathered Friends Hummingbird YF 20 above.
The Western Mountaineering Flylite above is a trimmed-down ultralight bag for warmer temperatures, but the UltraLite is the brand's more versatile and fully featured option. With a very healthy 16 ounces of 850-fill down, this is a great choice for shoulder season adventures and lower-48 alpine conditions. Unlike the minimalist Flylite, you get a wrap-around draft collar, full-length #5 YKK zipper, and a plush 5 inches of down loft. All in all, the longstanding UltraLite is Western Mountaineering’s most popular 3-season backpacking bag and for good reason.
Compared to the 20-degree version of the Feathered Friends Hummingbird YF above, the UltraLite has a thinner shell at 12 denier (the Hummingbird's is 20D), comes with slightly lower-quality down, and weighs around 3 ounces more. That said, we think Western Mountaineering’s shell fabrics are a little softer than Feathered Friends, which makes the UltraLite arguably the most comfortable 20-degree bag on the market. For more room, the Alpinlite is a wider version of this bag, giving you an extra 5 inches of girth in the shoulders and 4 inches more in hips while only adding 2 ounces of total weight.
See the Western Mountaineering UltraLite
Temperature rating: 40°F ISO Comfort, 31°F Lower Limit
Weight: 2 lb. 2 oz.
Fill: 17 oz. of synthetic (PrimaLoft RISE)
What we like: A roomy and comfortable synthetic bag.
What we don’t: Bulky, although we do like the included compression sack.
For backpacking, we almost always favor down sleeping bags over synthetics—they pack down smaller and provide more warmth for the weight. Nemo attempted to bridge this gap by outfitting the Forte with relatively compressible PrimaLoft RISE insulation, and we think they did a good job overall with cutting bulk. In addition, the bag takes the generous shape and roominess of the popular Disco above, subs in a 40-degree ISO Comfort rating, and slashes a significant $100 off the price (compared to the 30-degree Disco). For a cozy synthetic bag for side sleepers and those who like a little extra room, the Forte is a nice choice.
Despite all of the positives, it’s still an uphill battle in comparing the Nemo Forte to a down sleeping bag. At the same temperature rating, a down bag will almost always be lighter and more packable. But the big selling point here is comfort compared to other synthetics: the heavier Marmot Trestles Elite Eco below is tapered like a traditional mummy bag, whereas the Forte offers noticeably more space around the elbows and knees. We also like the gills, which allow you to dump heat without unzipping the entire bag, and the included compression sack. All in all, the Forte isn’t perfect, but it’s another creative option from Nemo at a good price.
See the Nemo Forte 35 See the Women's Nemo Forte 35
Temperature rating: 27.1°F EN Comfort, 15.6°F Lower Limit
Weight: 2 lbs. 8 oz.
Fill: 20.8 oz. of 650-fill down
What we like: Lots of warmth for the price.
What we don’t: Relatively heavy.
Most sleeping bags in this price range are built for temperatures around freezing or higher. But those that run cold or want a little extra warmth for the shoulder seasons without breaking the bank, try the Marmot Sawtooth. This bag is warm, comfortable, and the 20.8 ounces of 650-fill down offer a nice compromise of performance and value. And with the added Down Defender treatment for water resistance, the Sawtooth is a well-thought-out and cozy backpacking sleeping bag for a reasonable $257.
Keep in mind that the 27-degree EN Comfort rating is ample for most backpacking jaunts into the mountains and won’t have you checking the forecast incessantly before the trip, but the Sawtooth may be overkill for warm summer conditions. And given that it’s not enough insulation for true winter camping, the Marmot is best for those who run cold or get out in spring and fall. Finally, compared to the Bishop Pass above, the Sawtooth is a bit heavier and pricier, although some will appreciate the short zipper on the right for ventilation and easy in and out. For a higher-fill-power option from Marmot, be sure to check out the more premium Hydrogen below.
See the Marmot Sawtooth 15 See the Women's Marmot Angel Fire 25
Temperature rating: 20°F
Weight: 2 lb. 4 oz.
Fill: 19 oz. of 650-fill down / Fireline ECO synthetic
What we like: Another option for side sleepers that is lighter than the Nemo Disco above.
What we don’t: Not as roomy as the Nemo.
For years, Nemo has dominated the market in sleeping bags built for side sleepers, but Big Agnes has come to the plate in 2021 with the new Sidewinder. There is a lot going on with this bag: it’s decently spacious, has a unique zipper designed to stay out of your way when you turn over, a large hood with excellent coverage no matter your sleeping position, and extra padding (via synthetic insulation) at the hip and foot, which are major ground contact points for those who sleep on their side. If you toss and turn at night, the design is much more functional than a traditional mummy bag and a viable competitor to the Nemo Disco above.
How does the Sidewinder differ from the Nemo Disco? Most notable is shape: the Big Agnes is slimmer in terms of dimensions at 61 inches in the shoulders and 55 inches at the hip (the Nemo is 64 and 59 inches, respectively). It’s hard to argue with the extra space, but the Sidewinder does clock in at 7 ounces less (with identical 650-fill down and 30D shell). And like the Nemo, it also features a custom pillow pocket, which keeps your camp pillow (or stuffed down jacket) in place throughout the night. With a good number of comfort-related differences, finicky sleepers may prefer to try both bags out before buying, but the Sidewinder is undeniably a great addition to the side-sleeper market and priced right at just $280.
See the Big Agnes Sidewinder SL 20 See the Women's Sidewinder SL 20
Temperature rating: 33.6°F EN Comfort, 24.4°F Lower Limit
Weight: 1 lb. 7.3 oz.
Fill: 10.9 oz. of 800-fill down
What we like: Light and comfortable.
What we don’t: Lower fill power and fill weight than our top picks.
Many of the bags on this list have temperature ratings in the 20-degree range—that’s the sweet spot for a 3-season all-rounder. But for summer backpacking where the temperature won’t really drop, the Marmot Hydrogen is a great way to save weight and money. This lightweight bag should keep you comfortable down to around freezing and a little colder in a pinch, which can work great for warm-weather backpacking trips into the mountains, and should be plenty for those staying at lower elevations. And less down fill means the total weight of the bag dips below 1.5 pounds.
Along with the Hydrogen, Marmot also offers the warmer Helium (13.5°F EN Lower Limit) and winter-weight Lithium (-4.5°F EN Lower Limit). All use 800-fill goose down instead of the 850- or 900/950-fill of Western Mountaineering or Feathered Friends respectively, but Marmot has a good formula going with these backpacking bags. If you like other Marmot products, we bet you’ll enjoy the Hydrogen too.
See the Marmot Hydrogen 30
Temperature rating: 32°F EN Comfort, 20°F Lower Limit
Weight: 1 lb. 4 oz.
Fill: 13 oz. of 900-fill down
What we like: An ultralight mummy bag with an incredibly small packed size.
What we don’t: Narrow cut with little insulation on the bottom.
Therm-a-Rest knows a thing or two about sleeping in the backcountry, and the ultralight Hyperion is case in point. The specs on this sleeping bag are staggering: a 20-degree Lower Limit rating, 900-fill goose down, and a total weight of just 1 pound 4 ounces (that’s not a misprint). That's on par with the hoodless Feathered Friends Tanager (1 lb. 2.6 oz.) above, which is quite impressive given the Hyperion's hood and zipper. And did we mention the incredibly small packed size? See the photo in our buying advice below for proof.
How is Therm-a-Rest able to achieve this all with the Hyperion? The answer is a very aggressive design that is heavily tapered (read: not super roomy), along with patterning 70 percent of the down fill on top of the body. This means that you should bring along a sleeping pad with a decent R-value to insulate you from the ground, and if you happen to turn over on your side and bring the bag with you, you’ll likely get cold. What's more, the Hyperion features a half-length zipper, which is great for saving weight but offers little option for venting on warm nights (that said, it's a step up from the zipperless Tanager). It's a fairly compromised design, but the Therm-a-Rest is nevertheless a premium bag for ounce-counters who venture out in the shoulder seasons.
See the Therm-a-Rest Hyperion 20
Temperature rating: 35°F ISO Comfort, 25°F Lower Limit
Weight: 2 lb. 7 oz.
Fill: 16.6 oz. of 600-fill down
What we like: A quality budget bag that is a bit lighter than the Kelty Cosmic above.
What we don’t: You can go cheaper for the same level of warmth.
The Magma above has been REI’s premium sleeping bag for years, but the Co-op offers another nice value in the mid-range Down Time 25. Made with 600-fill-power down and a relatively hardwearing 30-denier shell, it’s a great option for weekend backpacking trips and those who don’t require the absolute lightest and most packable gear. Perhaps most importantly, the Down Time comes in at a very reasonable $199, which is a good price for a quality down bag that is environmentally friendly to boot.
The main competitor to the REI Down Time is the Kelty Cosmic above, which is our top budget pick. In the end, the Kelty is a significant $60 cheaper and slightly warmer with a 33°F ISO Comfort rating, but it's also 3 ounces heavier and has a thinner 20-denier shell. Given that a sleeping bag is one item where we aren’t particularly worried about denier (it’s only used on the inside of your tent), we give the slight nod to the cheaper Kelty. But for those who backpack with their dog, are hard on their gear, or prefer REI products in general, the Down Time is a nice option.
See the REI Co-op Down Time 25 See the Women's REI Co-op Down Time 25
Temperature rating: 44°F EN Comfort, 40°F Lower Limit
Weight: 12 oz.
Fill: 6.3 oz. of 850-fill down
What we like: Crazy light and the wet-weather assurance of hydrophobic down.
What we don’t: Only recommended for mid-summer use.
If you think the Flylite or Tanager above are ultralight, you ain’t seen nothing yet. At just 12 ounces, the 40-degree Spark is the lightest sleeping bag on this list and comes complete with a hood and zipper. What’s more, it features hydrophobic down and packs smaller than a 1-liter Nalgene in the included compression sack. Sure, the Spark can’t compare with most of the picks here in terms of warmth—we only recommend it for balmy summer nights—but these specs undeniably are impressive, even for a 40-degree bag.
The Spark is a standout in warmth for its weight, but it’s certainly not for everyone. In particular, we’ve found that we really prefer a full zip (or quilt) for venting on warm nights. On the other hand, the Tanager contains twice the amount of down as the Spark, making it the more versatile choice for 3-season use (40˚F is the Sea to Summit’s Lower Limit). Further, the Spark’s sewn-through construction is vulnerable to drafts, which the more premium baffled designs of the Flylite and Tanager eliminate. But for just $319, it offers considerable savings compared to the Western Mountaineering and Feathered Friends, and gets the job done for weight-conscious thru-hikers, fastpackers, and bikepackers alike.
See the Sea to Summit Spark 40 See the Women's Sea to Summit Flame 48
Temperature rating: 32.2°F EN Comfort, 21.6°F Lower Limit
Weight: 2 lbs. 6 oz.
Fill: 25 oz. of synthetic (HL-ElixR Eco Micro)
What we like: Good build quality and comfort.
What we don’t: At this price point, we prefer the down Kelty Cosmic above.
Marmot has been a mainstay in the world of synthetic sleeping bags for years with its varied Trestles line. For $158, the Elite Eco 20 offers a very practical 32-degree EN Comfort rating, which should work well for most 3-season conditions, along with a respectable weight of 2 pounds 6 ounces. Marmot has improved the Trestles of late by adding HL-ElixR Eco Micro insulation that is made from recycled fibers, and you get a draft tube, which is a rarity at this price point. And with the added moisture resistance of synthetic insulation, the Trestles Elite Eco is a comfortable sleeping bag that costs a fraction of the premium down options on this list.
In the end, we have the Marmot Trestles Elite Eco ranked here because we think there are far better options for backpacking, and the price of the Elite Eco is getting up there for a synthetic bag. For those who don't need the added warmth, Marmot's standard Trestles (30˚F) is significantly cheaper at $99, and the Nemo Forte above is the more comfortable option (and comes in a 20˚F version if you want to match the warmth of the Marmot). Alternatively, the down-filled Kelty Cosmic above is around the same price and weight but will pack down smaller and last significantly longer (synthetic fill has a tendency to pack out over time). Unless water resistance is particularly important to you, we recommend going with the Kelty.
See the Marmot Trestles Elite Eco 20 See the Women's Trestles Elite Eco 20
|Sleeping Bag||Price||Temp*||Weight||Fill||Shoulder/ Hip Girth||Shell|
|FF Hummingbird YF 20||$449||20°F||1 lb. 10 oz.||14 oz. of 900-fill down||58/52 in.||20D|
|Nemo Disco 15||$300||25°F (ISO)||2 lb. 11 oz.||22 oz. of 650-fill down||64/59 in.||30D|
|Western Mountaineering Flylite||$425||36˚F||14.3 oz.||7.7 oz. of 850-fill down||59/51 in.||10D|
|Kelty Cosmic 20||$140||33°F (ISO)||2 lb. 10 oz.||16.4 oz. of 550-fill down||62/58 in.||20D|
|Enlightened Equip Enigma 30||$290||30˚F||1 lb. 2 oz.||12.4 oz. of 850-fill down||Various||10D|
|REI Co-op Magma 15||$389||28°F (ISO)||1 lb. 12 oz.||15.9 oz. of 850-fill down||63/57 in.||15D|
|Feathered Friends Tanager 20||$399||20°F||1 lb. 3 oz.||12.6 oz. of 950-fill down||62/52 in.||7D x 5D|
|MH Bishop Pass 15||$240||26°F (ISO)||2 lb. 5 oz.||650-fill down||62/53 in.||20D|
|W Mountaineering UltraLite||$525||20°F||1 lb. 13 oz.||16 oz. of 850-fill down||59/51 in.||12D|
|Nemo Forte 35||$160||40°F (ISO)||2 lb. 2 oz.||17 oz. of synthetic||64/59 in.||30D|
|Marmot Sawtooth 15||$257||27°F (EN)||2 lb. 8 oz.||20.8 oz. of 650-fill down||62/57 in.||20D|
|Big Agnes Sidewinder SL 20||$280||20°F||2 lb. 4 oz.||19 oz. of 650-fill down||61/55 in.||3oD|
|Marmot Hydrogen 30||$341||34°F (EN)||1 lb. 7 oz.||10.9 oz. of 800-fill down||61/56 in.||20D|
|Therm-a-Rest Hyperion 20||$420||32˚F (EN)||1 lb. 4 oz.||13 oz. of 900-fill down||57/49.5 in.||10D|
|REI Co-op Down Time 25||$199||35°F (ISO)||2 lb. 7 oz.||16.6 oz. of 600-fill down||62/58 in.||30D|
|Sea to Summit Spark 40||$319||44°F (EN)||12 oz.||6.3 oz. of 850-fill down||58/50 in.||10D|
|Marmot Trestles Elite Eco 20||$158||32°F (EN)||2 lb. 6 oz.||25 oz. of synthetic||62/57 in.||20D|
*Editor's Note: For the purposes of this table, we have included the EN or ISO Comfort rating, which we feel is the most accurate point of comparison. When available, we've listed both the Comfort and Lower Limit in the product specs above. For more on the differences, see our buying advice below.
- Sleeping Bag Temperature Ratings
- Sleeping Bag Insulation
- Hydrophobic Down and Water-Resistant Fabrics
- Weight and Packability
- Durability and Shell Denier (D)
- Sleeping Bag Dimensions
- Women's-Specific Sleeping Bags
- Maximizing Your Bag's Warmth
- Backpacking Sleeping Quilts
The single most important decision you’ll make when choosing a sleeping bag is the temperature rating. Simply put, few things are worse than a long, sleepless night shivering inside your tent, and we always believe that it’s best to err on the side of caution when choosing your bag. Below we break down what you need to know about temperature ratings, including the EN/ISO standard, non-standardized models from cottage brands, and how to choose the right rating.
The EN/ISO Rating System Explained
Instead of depending on the manufacturer and their marketing whims for a temperature rating, the sleeping bag industry has attempted to standardize the system with the help of the EN (European Norm) and, more recently, the ISO (International Organization for Standardization). This criterion (formerly known as EN 13537 and now known as ISO 23537) lays out guidelines for how to test the warmth of a bag and enables consumers to make accurate comparisons between products. Both standards give us four numbers—upper limit, comfort, lower limit, and extreme. The middle two ratings have the most significance for the majority of backpackers:
Comfort Rating: The temperature at which an average woman can sleep comfortably. Generally, women sleep colder than men, hence the importance of the comfort rating.
Lower Limit: The temperature at which an average man can sleep for eight hours without waking. We rarely sleep for eight hours without waking on a backpacking trip, but you get the idea.
Of course, all of the EN/ISO ratings are based on averages and in general we've found them to be rather optimistic. As such, we've found that the higher EN/ISO Comfort rating is a better basis for across-the-board comparison than the EN/ISO Lower Limit, and therefore have listed it in the comparison table above (both ratings are included in the product specs when applicable).
Sleeping Bags Without an EN/ISO Rating
Some manufacturers—typically smaller companies like Western Mountaineering, Feathered Friends, and Enlightened Equipment—do not submit their bags for EN/ISO testing. From our experiences, these brands actually are on the conservative side and take pride in offering very realistic temperature ratings. For example, the Feathered Friends Hummingbird YF 20 is a very warm bag that has kept our tester (an average male) comfortable into the 20s, whereas the Kelty Cosmic 20—with a 21°F ISO Lower Limit—will be cold if temperatures dip below freezing. As a result, we've found that in most cases the EN/ISO Comfort rating (the Cosmic's is 32˚F) offers the best point of comparison to unrated designs.
Choosing the Right Temperature Rating
In choosing your bag’s temperature rating, you'll want to look specifically at the EN/ISO numbers (when applicable), not just the temperature included in the name of the bag. As we touched on above, we recommend using the Comfort rating as the more realistic of the two numbers. And for non-EN/ISO-rated bags from high-end manufacturer's like Feathered Friends and Western Mountaineering, you can just utilize their listed rating. In both cases, it's also a good idea to leave a reasonable buffer (10 degrees or more) to be safe. For example, if you anticipate nighttime lows around freezing (32˚F), you’ll want to aim for a bag that's rated at 20 to 25 degrees. Other factors to consider are your age (people typically don’t sleep as warm the older they get), whether you are a cold or warm sleeper (gender can factor in here too), and whether you’ll be sleeping in a tent or open-air.
The majority of backpacking sleeping bags (including most of the models on the list above) are of the 3-season variety, with ratings from around 20 to 30 degrees Fahrenheit. We love the versatility of these designs: in the summer, you can unzip the bag and stay reasonably cool, but they also allow for spring, fall, and alpine backpacking when the temperature drops to freezing or below. Summer bags have lower limits around 40 degrees and offer the least room for error, but keep weight low for warm-weather use at low elevations. Finally, winter or expedition bags are the warmest of all and overkill for most recreational backpackers (we don’t include any here). Within this category, a model like the 0-degree Feathered Friends Snowbunting EX is a good choice, and there are a number of options from climbing-centric companies like Western Mountaineering and Montbell that are rated down to -10 degrees Fahrenheit and lower.
Down vs. Synthetic Insulation
The down vs. synthetic debate is not unique to backpacking sleeping bags. Midlayers, camping bags, and even sleeping pads are all insulated with these fill types. For a certain piece of gear or apparel, one has the leg up on the other, and for backpacking sleeping bags, we still give the clear edge to down fill. There are a few major reasons for that, including the best warmth-to-weight ratio, far better packability (i.e., a smaller compressed size), and a more premium warmth. The last one is a bit subjective, but it’s a clear consensus from us that down’s lofty warmth feels more luxurious. Down does vary in quality, which is measured in fill power (covered below), but even a mid-grade down fill is the superior insulator.
So why consider synthetic? The most common reason for most is price. Even a premium synthetic bag like the Nemo Forte 35 easily slides in close to $200, while a nice down bag doubles that (and more). In addition, synthetic performs far better than down in wet weather. While there have been improvements in down’s performance in the wet thanks to the application of hydrophobic coatings on the feathers, synthetic will insulate far better if moisture enters the bag. So, for starting out, if you’re looking for a budget option, or you backpack in really wet conditions, synthetic bags remain a great choice. For an even more in-depth explanation of this topic, see our article on down vs. synthetic insulation.
Down Quality: Fill Power
If you decide down is going to be your insulation of choice, one of the first specs to look at is the quality of a specific down, known as its fill power. Specifically, it’s a measure of how much loft or fluffiness the down clusters have, and this correlates with warmth (note: both duck and goose down are measured in the same way). The highest down fill power is 1,000, and you’ll see cheaper sleeping bags closer to 500. Generally, the higher the fill power, the more expensive the sleeping bag. The lower the fill power, the more it must weigh to provide similar levels of warmth. High fill powers in the 800 and 900s are great, but don’t necessarily be turned off by 550- or 600-fill—it’s a great way to save money on an otherwise excellent bag.
Down and Synthetic Fill Weight
Fill weight is the actual amount of insulation stuffed into a sleeping bag. If it’s a close call between two bags with the same types of insulation (down or synthetic) and one or both don’t have EN or ISO ratings, you can compare fill weight to get a better idea of which one will be warmer. Cut does matter here: a bag with a slender cut may have less insulation than a bag with a roomy cut despite providing similar or even more warmth. Fill weight is more helpful for a category like down jackets, which don’t have EN/ISO ratings, but it’s good to know here too. And it's a good visual for how much more insulation is required for a synthetic bag to compete with down. For comparison, the Nemo Forte requires 6 additional ounces to achieve approximately the same temperature rating as the down-filled Disco.
Down feathers lose much of their ability to insulate when wet, so manufacturers have taken strides to provide built-in protection in the form of hydrophobic down and water-resistant shell fabrics. In the case of hydrophobic down, the feathers are coated with a polymer that protects them from moisture and keeps them from clumping. In use, this means you don’t have to worry as much about brushes with water inside or outside of your backpacking tent—although you still don’t want to fully soak your bag. Hydrophobic down adds a little weight but we’re big fans overall, especially for those headed out in wet areas like the Pacific Northwest or New Zealand.
Some sleeping bags also employ water-resistant shell fabrics in order to keep moisture at bay. We see this in bags like the Feathered Friends Hummingbird YF, which features a Pertex Quantum shell with YFuse technology and a durable water repellent (DWR) finish. The goal of this combination is to bead up moisture and roll it off rather than allowing it to soak through to the down feathers beneath. Whether you’re opting for a bag with hydrophobic feathers, water-resistant fabrics, or both, it’s important to remember that these technologies protect against light—think condensation in a tent or dew during an open-air bivy—and will do little to keep you dry and warm in sustained or heavy rain.
Along with your backpacking tent, your sleeping bag is one the heaviest and bulkiest items in your pack. The models here run the gamut from just 12 ounces for the ultralight Sea to Summit Spark 40, to 2 pounds 11 ounces for the roomy and warm Nemo Disco 15 (which uses heavy 650-fill down). In general, weight is saved by using premium fill-power down (800+), thin shell fabrics and zippers (often half-length), and trimmer profiles. As is the case with virtually all categories of outdoor gear, ultralight products tend to be among the priciest on the market. To better evaluate and compare weights, we’ve included this key spec in each product write-up and our sleeping bag comparison table above.
In terms of packability, it’s another big selling point of premium down. Natural goose and duck down compresses in a way unmatched by any synthetic, and it’s not even close. In general, higher-end down bags like the Feathered Friends Tanager and Western Mountaineering Flylite will be the most compressible due to the loft of the down and use of thinner shell fabrics. Lower fill-power down and synthetic bags will be the least compressible options. Other indicators include the cut of the bag—a tapered cut will trim fabric and stuffed size—as well as the temperature rating (warmer bags have more insulation). Summer bags can get away with using less insulation and will be highly compressible as a result.
To take full advantage of the small stuffed size potential of your sleeping bag, consider picking up a compression sack (one of our favorites due to its waterproof construction is the Sea to Summit eVent Compression Dry Sack). Most sleeping bags only include a non-compressible stuff sack, but this won’t do your sleeping bag justice in terms of how small it can get. Do take care when using a compression sack—try to lightly compress the bag so that it fits easily into your pack without overdoing it, and don’t store your sleeping bag in a compression sack for extended periods as that can permanently damage the down.
For sleeping bags, durability is commonly measured by the denier (D) of the shell fabric, which represents its thickness, and the higher the number the thicker the thread. At the ultralight end of the spectrum, the Feathered Friends Tanager 20 uses an incredibly thin 7D x 5D fabric, which you literally can see the feathers through. On the other hand, most 3-season sleeping bags fall somewhere in the 10D to 30D range. In general, sleeping bags are one type of outdoor gear that we don’t worry much about in terms of denier. Your bag goes from storage, to the bottom of your pack, directly into your tent. Unless you bring your dog inside your tent or haul the bag out by the campfire for extra warmth, we’ve seldom punctured our sleeping bag. That said, given their high cost, it’s unfortunate if you do (we always pack repair tape in case), so take care with the surrounding gear inside your pack and tent.
In addition to considerations like warmth and down fill, the cut of a sleeping bag is a very important piece to analyze. The three most common points of measurement for sleeping bags are the girth (i.e. circumference) at the shoulders, hips, and feet (59"/51"/38", for example), which give you an idea as to how roomy or tapered the bag is. The shoulder and hip measurements are the most significant in terms of comfort, which is why we’ve included them in the comparison table above.
Many ultralight sleeping bags save weight by tapering the cut for less fabric and down. If you toss and turn at night or just prefer more space, make sure to consider a roomier bag (the spoon-shaped Nemo Disco 15 is a great example). The downsides are that these bags can feel draftier and may not retain heat quite as well, and often weigh more because more fabric and insulation are required to fill the larger surface area. The good news is that many manufacturers make the same bag in varying widths. The Western Mountaineering Alpinlite is the wider version of the UltraLite, for example, and the Feathered Friends Swallow and Swift expand on the dimensions of our top-ranked Hummingbird.
In terms of length, most sleeping bags come in two or three lengths that are meant to fit men and women of varying heights. For men’s bags, the regular size often is 72 inches long and the tall is 78 inches long. If the bag doesn’t have a women’s-specific version, you’ll often see a short 66-inch option. If you are on the border and want the hood to extend over your head, it’s a good idea to size up. Keep in mind that larger sizes do cost and weigh more and have a larger packed size.
Some backpacking bags have a women’s-specific version with a different name, and others simply have a “short” version of the same bag. What can you expect with a women’s-specific bag? They usually have a slightly different cut than men’s or unisex models that is narrower at the shoulders and roomier around the hips. Further, the bags will have a little more insulation (often in targeted areas) and are often advertised with their comfort rating rather than their lower limit. For example, the men’s REI Co-op Magma 15 has a comfort rating of 28 degrees, while the women’s version is 17 degrees (their lower limits are 16˚F and 3˚F, respectively). All in all, we know women that buy women’s bags and others that buy men’s or unisex bags when they fit. The differences are small and it’s mostly a matter a taste.
Once you purchase your bag, there are a few things to keep in mind in order to maximize warmth. Perhaps the most important consideration is your sleeping pad’s R-value, which offers a measurement of how well the pad insulates you from the ground. R-values range from 1.0 (almost no insulation) to about 9.5 (winter-ready warmth), and the average 3-season backpacker should look for something in the 3 to 4 range or more. Next up, eliminating drafts can go a long way—on a cold night, make sure your zipper is closed all the way and cinch the draft collar and hood close to your neck and face. It’s also a good idea to have some extra clothing in case you need it: a warm hat can help keep a lot of heat in, and some wool baselayers will help add some warmth as well (we advise against cotton). Finally, you’ll want to be sure to get the right sized bag, which we address in the "Dimensions" section above.
Sleeping quilts fall into a different category than sleeping bags, but they’re worth mentioning for those who run particularly warm or want a lighter option. A sleeping quilt (we include the Enlightened Equipment Enigma above, but you can find all of our recommendations in our buyer’s guide to the best ultralight sleeping bags and quilts) is a minimalist backcountry sleep system popular among ultralighters and thru-hikers, characterized by an open back (read: no zipper) and emphasis on weight savings. Quilts feature enclosed or cinchable footboxes, connect to your sleeping pad via included straps, and cinch around the neck to provide wrap-around and (hopefully) draft-free protection.
The sleeping bag vs. quilt debate comes down to personal preference. Some backpackers (including one of our editors) swear by quilts and love that they’re lightweight, focus the insulation on top of the body (your sleeping pad should take care of the underside), and ventilate well on warm nights. But not everyone is keen on the compromises: you have to bring proper head coverage (a beanie will do), the quilt/sleeping pad system isn’t always perfect and can let in drafts, and you might feel particularly vulnerable on cold nights. All in all, most recreational backpackers will prefer the coziness and simplicity of a lightweight mummy bag, but quilts are a viable option and especially great for warm nights.
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