The Best Ultralight Backpacking Sleeping Bag of 2021

A good night’s sleep is critical for a great day on the trail. Waking up feeling refreshed and ready to tackle some miles sure beats dragging yourself out of your tent after tossing and turning all night.

Sleep is critical, so you need to shop wisely when choosing essentials like your sleeping bag. We’re here to help with some tips, tricks, and recommendations to help you pick the best sleeping bag for your next adventure.

Best Ultralight Sleeping Bags

WESTERN MOUNTAINEERING UltraLite

Weight: 1 lb 13 oz
Warmth Rating: 20°F / -7°C
Fill: 16 oz / 453 g Down
Price: $525

An efficient mummy sleeping bag that will keep you cozy in different climates, the UltraLite features a full down collar to help seal in the heat around your neck without adding excess bulk.

High lofting down (16oz.) pumps the bag to 5″ and it has a full-length YKK zipper. It comes in 3 different sizes ranging from 5’6″, 6′ and 6’6″ with a shoulder girth of 59″ or 60″ in regard to the 6’6″ sleeping bag.

REI Co-op Magma 15 Sleeping Bag – Men’s

Weight: 1 lb 12 oz
Warmth Rating: 16°F / -8.9°C
Fill: 850 g Goose Down
Price: $379

Giving you the best warmth-to-weight ratio, the Co-op Magma 15 sleeping bag has lightweight construction, water-resistant goose down and generous knee and foot space with a fitted silhouette.

Cozy and super soft with its Downproof Pertex shell, its variable baffle spacing delivers high thermal efficiency. The zipper cover and internal anti-snag strip make for easy zipping and the contoured hood keeps you warm, with enough space for a low-profile pillow.

There are 2 hood drawcords to allow for internal adjustment and an insulated yoke that fills the neck and shoulder gap, all of which help prevent heat loss. Coming in 3 sizes you can choose from “fitted” with a narrow profile for those on the skinny side who need more warmth, a “regular” that has a wider cut providing wriggle room and a “relaxed” version which is super roomy for those that prioritize comfort above all else.

REI Co-op Igneo 17

Weight: 1lb 15 oz
Warmth Rating: 17°F / -8°C
Fill: 700 g Duck Down
Price: $299

Another sleeping bag under the label of REI Co-op is the Igneo 17 mummy sleeping bag with water-repellent down plus breathable fabric panels to create a sleeping bag perfect for wet conditions. Suitable for 3-season use, it offers superior loft and warmth with a Ripstop nylon shell of DWR finish.

With a contoured and slightly angular hood, the headspace is nice and warm – like a less constricting mummy design. Complete with a full-length draft tube to keep you warm.

MONTBELL Seamless Down Hugger 900

Weight: 1 lb 11.6 oz
Warmth Rating: 17℉ / -8°C
Fill: 900 EX Down
Price: $669.00

Really love the Seamless Down Hugger 900 #1. While this bag is one of the more expensive bags on the list, it is also one of the most quality.

Instead of baffles, Montbell uses their proprietary Spider Baffle System to hold the down in place and preserve the loft of the bag. Stitching is known to create cold spots and let warm air out of the bag; the seamless design solves that and guarantees maximum insulation. The few stitches that remain are slightly elasticized which makes adjusting sleeping positions very easy to do in the middle of the night.

Besides its innovative design, the Down Hugger 900 does a great job at repelling water and moisture. The #3 and #5 models use a GORE-TEX INFINIUM WINDSTOPPER fabric while the #1 is made out of DWR-treated Ballistic Airlight nylon.

It also comes complete with a neck baffle, insulated draft tubes and extremely smooth zippers. It’s these little extras that give the Down Hugger an edge over other bags. The mummy head and tapered bottom will ensure you maximize heat efficiency.

SEA TO SUMMIT Spark Ultralight

Weight: 1 lb 7.5 oz
Warmth Rating: 18°F / -8°C
Fill: 850+ loft Ultra-Dry Down (90/10 European goose down)
Price: $479

With a shell of 10D UL nylon treated with DWR and a soft liner with a high-density weave, this sleeping bag has a transverse baffle construction and a contoured hood with a draw-cord that you can tighten to actually cover most of your head if you want to really keep the heat in. Coming in 3 different weights, it is a no frills, top of the range option if you are looking for weight versus warmth.

It has a one-directional 1/3 length zip with a toggle at the head to allow you to totally cocoon yourself and that is it. This sleeping bag will only give you the essential elements.

Great for ultralight hiking and alpine climbing, it is a compact sleeping bag that will take up little space in your bag once it is put into its compression sack, that you can compress further with the use of 4 toggles.

Nemo Disco Down Sleeping Bag

Weight: 2 lbs 11 oz
Warmth Rating: 15 F / -9°C
Fill: 650 FP Down
Price: $299

The NEMO Disco is a comfortable 2-season mummy bag with interesting design features. This sleeping was built with extra room at the elbows and knees to provide side-sleepers with more mobility and comfort. The integrated pillow sleeve and the zippered stash pocket are nice additions. The bag also includes a blanket fold that protects your neck and face against cold drafts.

For ventilation, NEMO designed two zippered “gills” in the body of the Disco. In warmer weather, these can be unzipped instead of the main zipper to regulate the temperature inside of the sleeping bag.

The NEMO Disco is available in 15 and 30F temperature ratings and comes with a lifetime warranty.

SIERRA DESIGNS Backcountry Bed

Weight: 2 lbs 8 oz
Warmth Rating: 27°F / -3°C
Fill: 700FP PFC-Free Dridown
Price: $239.95

Coming in a regular and long size, the Backcountry Bed is an award-winning sleeping bag with a contoured shape and a zipperless design for more comfort.

Thermally efficient and lightweight sleeping bag, it has an oversized integrated comforter to give you all the comforts of a snug bed, just like home.

There are insulated hand and arm pockets and a stretch cord closure system to seal out the drafts. The self-sealing foot vents enable fast and easy ventilation. The sleeping pad sleeve will keep your pad where it is meant to be under you, to improve your overall comfort during the night.

MOUNTAIN HARDWEAR Phantom 15

Weight: 2 lbs 1.2 oz
Warmth Rating: 15°F / -9°C
Fill: 850-fill goose down
Price: $520

The unisex Mountain Hardwear Phantom eliminates cold spots caused by traditional stitching and puts the warmth where you need it most, around your core and your feet.

A mummy-cut sleeping bag with face gasket and anti-snag side zipper, this bag compresses well and maintains an excellent loft. An ergonomic draft collar prevents the escape of warm air from inside the sleeping bag and the comfortable footbox gives you a natural foot position to ensure that you are comfy and toasty. The performance mummy cut does give you a snug fit by reducing girth, weight, and bulk, whilst maximizing thermal efficiency.

It comes in 3 sizes: regular, long, and short and is one of the best lightweight sleeping bags available. If you can afford it, this sleeping bag is an excellent ultralight, compressible and very comfortable option to consider.

For a cheaper (but heavier) alternative, check out Mountain Hardwear’s Bishop Pass 15 mummy bag.

Your Sleeping Bag Requirements…

LIGHTWEIGHT: NOTHING OVER 3 LBS

Unless you are doing some alpine backpacking in sub-zero temperatures, your bag should be able to provide adequate insulation without tipping the scale.

Sleeping bags are one of the “Big 3” backpacking gear items (tent and backpack being the other two) and are, therefore, one of your biggest opportunities to save weight. Most gear items weigh under a pound meaning different models and brands of that item might only differ by an ounce or two.

Sleeping bag models, on the other hand, can vary by several pounds. AKA – be mindful of this before getting a 5 lb. bag. As you can imagine, high-quality and lightweight sleeping bags are a premium gear item… and the price can reflect this.

COMPRESSIBLE: GET RID OF THE BULK

This will vary a lot depending on your warmth and insulation needs. ie – a summer bag will compress smaller than a winter bag. By far, the number one thing that will account for the size of your bag is the insulation fill. The fabric and design elements being the second and third. Down and synthetic fillings both have pros and cons (we’ll get there in a sec), but down-filled sleeping bags pack down to the smallest sizes.

Compression straps and stuff sacks can significantly cut down on the volume your bag occupies in your pack. Ideally, you want it compressed as compact as possible while on the trail.

Packed 20 degrees down sleeping bag

ADEQUATE WARMTH: BUILD IN THE “20-DEGREE RULE OF COMFORT”

Try to think of the degree ratings as only accurate for survival situations. For example: if you see “Awesome Model 20”, that means you will be able to survive in the sleeping bag if the temperature drops to 20 degrees Fahrenheit. Note this survival rating is a much lower threshold than what is actually comfortable to sleep in.

For me, I add about 20 degrees to the manufacturer’s claim for a comfortable night’s sleep. So, to continue with this same 20-degree bag example, I’d probably only feel comfortable sleeping in it in 40-degree weather (20 + 20 = 40), without an additional liner or warm clothes.

Therefore, keep in mind how cold your nights will be, whether you are a hot or cold sleeper, what clothes you like to sleep in, and whether you will be in a tent or not.

TEMPERATURE RATINGS: KNOW HOW THEY’RE RATED

Temperature ratings on sleeping bags should be considered as a guideline only, as seasonal marked sleeping bags will differ depending on what region or country you are in. Examples: Summer (32° and higher), Winter (10° and lower), and 3-Season (10° to 32°).

Look for sleeping bags tested according to EN Standards and marked EN13537, which means the sleeping bag has undergone a “thermal manikin” test (which is a human model designed for scientific testing), not just independently tested by the manufacturer. Think of it as measuring the insulation, like the walls of a house.

The tests are conducted on the basis that a person is using a sleeping pad, is cocooned into a tent, and is wearing one layer of thermal underwear. A “standard” man is aged 25, 1.73 m in height, and weighs 73 kg, whilst a “standard” female is aged 25, 1.6 m tall and weighs 60 kg. Keep in mind that a man normally sleeps “hotter” than a female and that everyone is a different shape and size, with different levels of “self” insulation.

There are 4 standard temperature ratings to keep you warm:

Upper Limit—when a male can sleep without sweating, with hood and zippers open and his arms outside of the bag.
Comfort—this is when a female can comfortably sleep in a relaxed position.
Lower Limit—the temperature a male can sleep uninterrupted for 8 hours in a curled position.
Extreme—this is the minimum temperature for a female for 6 hours without the risk of death from hypothermia – albeit a touch of frostbite is still a possibility.

Sleeping bags with an EN Standards tag will affect the price of the sleeping bag because the process is expensive. Always bear in mind that no amount of testing will be 100% accurate for you as an individual, as we all feel the cold differently. You can always take a layer of clothing off or unzip your bag if you get too hot, or simply add another layer of thermals and completely duck inside your sleeping bag if you happen to be on the cold side.

SPACIOUS INTERIOR: NO BOA CONSTRICTORS

After a long day of hiking, I really don’t want to be confined to a tight cocoon in my tent. Many ultralight sleeping bags cut weight by making them narrow. This is a tough balancing act – space versus overall weight and bulk.

A snug sleeping bag will be warmer, as it minimizes the air space around your body, but you don’t want to feel like you are in a straight jacket. Spacious sleeping bags give you freedom of movement, which is a dire necessity for restless souls, but they also require more precious body heat to fill.

There are 3 key measurements to take into consideration:

Length – opt for the shortest length that will fit your frame (to save weight), but ensure that your feet are comfy without being squished when you have the hood done up, as this will compress the insulation, which is what you don’t want. Having a bit of extra room at the bottom of your backpacking sleeping bag gives you the option of having somewhere to stash some clothes and/or your hiking shoes. The regular male sleeping bags come in 2 standard lengths – up to 6ft and up to 6ft 6in. Female sleeping bags are usually up to 5ft 4ins and 5ft 10ins. When in doubt, get the extra length.
Shoulder girth – most of the male sleeping bags have a shoulder width of between 60 and 64 inches with narrow ones coming in at 58 inches. Female ones are slightly narrower ranging from 56 to 60 inches. An inch can make a huge difference on the snug level. The best way to determine the size you need is to test-drive a few different sized sleeping bags.
Hip measurement – most men’s sleeping bag will measure in around 58 inches, whilst the women’s tend to be a bit higher around 60 inches. Again, take a couple of sleeping bags for a test-drive.

ZIPPERS: EASY ENTRY AND EXIT

You will get in and out of your sleeping bag a lot, potentially several times at night. Think for a second about where you typically sleep at night on the trail… in a small tent, possibly next to your partner, in the dark. Fumbling around with a snaggy zipper is the last thing you want.

Long length zippers, preferably opening on both sides so you can utilize both hands to read your Kindle book or a map of the next day’s hike, are the best to go for. They also offer more flexibility for ventilation. But, some sleeping bags have short zipper lengths to cut down on weight. If having your body fixed and constricted all the time doesn’t bother you, then a short zipper could be an ultralight option.

Steer clear of metal zippers, as you need a zipper to be durable and reliable without the weight. Nylon and plastic zippers are the best for their quality, length, and ability to adapt to various weather conditions, while slider zippers have special characteristics.

Nylon (coil) zippers have teeth made of coiled monofilament giving them super horizontal strength, which allows them to be longer than an average zipper. They are lightweight and fire-resistant, with great durability, and are easy to repair.
Plastic zippers (aka vision) are commonly used in military equipment. The teeth of a vision zipper are made out of a specific type of plastic that is molded onto a zipper tape giving it durability as well as making it waterproof.
Slider zippers have the popular features of “double pulls” and a “non-locking” function enabling sleeping bags to be opened from both inside and outside, also giving quick and easy access to get in or out of the sleeping bags.

More and more of the best ultralight sleeping bags are going zipperless – after all, they are a breeze to open and close. Zippers can add weight and have the potential to wear out over time. If you do get one with a zipper, make sure it has a draft tube. This is a mini insulated flap to cover them, otherwise, exposed zipper seam.

Things to Consider…

FILL: DOWN VS SYNTHETIC INSULATION

Down feathers are lighter, warmer, and pack smaller than synthetic insulation options. Down has an Achilles heel though – it loses loft and insulation ability when it gets wet. Losing insulation is a scary thought for winter backpacking. Down is more durable than synthetic fillings, but super expensive.

Most down-filled sleeping bags have been treated with durable water repellent (DWR) in the factory process, which is fluoropolymer based and named “hydrophobic” down. This prevents the down filling from becoming a soggy mass with no ability to retain heat.

It is also known as “dry down”. This treatment makes it water-resistant not waterproof, so don’t expose your sleeping bag to a torrential thunderstorm or drop it into a stream. DWR will wear off over time and will require reapplying.

A synthetic insulated backpacking sleeping bag dries faster than down, it is non-allergenic and is less expensive to buy. On the minus side, the synthetic filling will give you less warmth for its weight, it is bulkier to carry and each time you compress it, the insulating power is reduced.

Technology has taken over from the old polyester fill for sleeping bags of the synthetic ilk and today there are 4 common primary fillers other than down.

Popular synthetic options on the market include:

PolarGuard and 3D PolarGuard Delta—PolarGuard was the original version with 3D PolarGuard Delta the perfected product that will give the same insulation ability, but with reduced bulkiness and weight. Commonly used in high-quality three-season sleeping bags, it is easy to take care of; when wet, it will not lose its insulation properties and you can wash it in cold water in a washing machine.
Quallofil—on the heavy and bulky side, you won’t see it in the lightweight or high-end priced sleeping bags.
Holofoil & Hollofil II—only used in bargain-basement sleeping bags as it lacks the insulating ability, is heavy, and quite bulky.
Thermolite—another cheapie sleeping bag filling with no insulation to keep you warm.

I keep my sleeping bag well protected in a waterproof stuff sack, inside a waterproof pack lined backpack, and I have never had a truly wet sleeping bag. If you can afford it and will keep it protected, I vote to go for down insulation along with protective storage.

FILL POWER: THE HIGHER THE NUMBER, THE GREATER THE INSULATION

‘Fill-power’ is a measurement of the density of down fill and accounts for the overall warmth-to-weight ratio. This typically ranges from 600 to 950. The higher the number, the more ‘quality’ the feather insulation is. It is calculated on how many cubic inches 1 ounce of down can fill a testing device.

And, of course, the higher the fill of power down, the more expensive it is. Generally, an 850 fill power or higher is in the top quality bracket with a warmth-to-weight ratio. Keep in mind that a 700-fill-power down sleeping bag rated +20°F will be lighter than a 600-fill-power down bag rated +20°F.

A 3-season sleeping bag normally has a rating of at least 600, but if you are planning on being in sub-zero whether you should be considering 900 to 1000-fill-power.

VERSATILITY: 3-SEASON VS. 4-SEASON SLEEPING BAGS

Should you buy 2 sleeping bags? One for the warmer months and one for the winter? If money is no issue, by all means, feel free to splurge. For the rest of us though, I think two is totally unnecessary. When in doubt, err on the warm side and get a full-on winter bag.

A winter bag can be compatible in summer, but a summer bag just won’t cut it in winter. If the thick winter sleeping bag is too hot on summer nights, unzip it or just sleep on top of it in your bag liner.

MUMMY VS QUILT: WHAT ARE THE DIFFERENCES?

Mummy bags are the traditional cocoon-like sleeping bags with an added headwrap that will only leave your smiling face exposed. Because of the additional head coverage, mummy bags can be warmer, but they can be constricting and don’t allow for a wide range of sleeping positions. They are often secured with drawcords or zippers.

Quilts are like big insulated blankets. Some are completely rectangular and have no zippers at all. Others are sort of a half-breed, with a foot box to tuck your feet into and some straps or clips to close the open wall of the blanket. Quilts generally allow more movement. They also provide a lot of flexibility if you want to just have half of the bag on your body on a warmer night.

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HOOD: A NICE TO HAVE

A hood covers your head and cinches tightly, leaving only your face exposed. It traps your body heat inside the bag, helping to keep you warm. Hoods are cozy when you sleep on your back, but can get in your way when you turn to the side or sleep on your stomach. I’m a side sleeper and on more than occasion, I’ve woken up in a panic with my head buried deep inside the hood…

PAD LOOPS AND SLEEVES: MORE COMMON WITH QUILTS

Connecting your sleeping bag to your sleeping pad, the pad loops are sewn-in straps whereby you can secure your sleeping bag and prevent it from slipping off the pad.

A padded sleeve is used as an insulated sleeping pad when the design of a lightweight sleeping bag has eliminated the bottom insulation to reduce overall pack weight, making it compress smaller than a conventional sleeping bag.

DRAFT COLLAR: EXTRA INSULATION AROUND THE FACE AND NECK

A draft collar is also known as face mufflers, a head gasket, or neck baffles and it is the insulated collar around the hood of a sleeping bag to guard against cold weather.

It is referring to the insulated baffles in the sleeping bag that sit around your head and neck to prevent heat from escaping or the cold leeching in. The drawcords are differentiated so that you can feel in the dark which one does what – loosens or tightens your hood.

Tips to Sleeping Warm and Cozy

Choose the right sleeping pad: A good sleeping pad not only provides an extra layer of cushioning but also insulates from the cold ground. The ability to insulate you is measured in the R-value of the sleeping pad. The higher the R-value, the warmer it is.
Remember to bring thicker ‘camp socks’ that you don’t use for hiking. It feels great to take your dirty socks off each night and swap them for a clean and comfy pair. Not only does it feel good, but it also will keep your feet warm and dry all night long.
Consider purchasing a sleeping bag liner. It adds some warmth and helps keep the inside of the bag clean as well.
Pack hand warmers to generate additional heat inside your bag. Alternatively, you can use a water bottle filled with warm water (or other things!). Just make sure the water bottle does not leak 😉
Make sure your tent’s rainfly is secured close to the ground. This will prevent a cold draft from making its way into your tent and helps retain as much body heat as possible.

Sleeping Bag Storage and Care

Storage: Do NOT keep your sleeping bag stored at home compressed in the stuff sack. Over time, this can significantly decrease the loft of the fill and turn your sleeping bag into a flat blanket. Less loft = less insulation.

Most bags come with a storage sack. They often mesh and large, about the size of a garbage bag. The whole idea is to keep your sleeping bag in a fluffy state as much as possible, only compressing it down when on the trail.

Care: Hang it in a closet or use the large mesh sack that came with the bag. When you return home from your trip, don’t store the sleeping bag if it is wet. A wet bag may develop mold which is impossible to remove. You should air-dry your bag until it is completely dry.

If it gets dirty, spot cleans it with warm water if possible and let it air dry. If you have to throw it into the washing machine, carefully wash it according to the manufacturer’s instructions. Avoid using household detergents as they damage the down or the hydrophobic coating. Choose cleansers, like those from Nikwax that will clean without causing any damage to the insulation.