Ultralight sleeping bags

Ultralight sleeping bags are the lightest, less burdensome bags available today. They weigh at most two pounds and half, depending on the model. And bike packers, backpackers and through-hikers love them for being very easy to pack and carry. These bags are optimal for keeping your packsack light and with extra room for other items. The hikers who like to walk a lot can increase their speed and mobility with these gears.

In general ultralight sleeping bags should weigh two pounds at most, as summer, or three-seasons models. However in this review we decided to present also some for winter, coming with a little more filling, and so weight. Expect to see also three pounds bags. The important thing is that the bag works for you, allows you to sleep comfortably and is light enough not to burden uselessly your activities, whatever they are.

You will see that to save as much weight as possible, all these bags have a mummy shape. So, consider they will have room enough for you and some little object you want to keep near, as your headlamp. Also, there won’t be a great space to move inside and turn. The priority is to have them ultralight. The hoodless bags are mostly for the good season, while for chilling nights we suggest to get a model with a hood to get a better protection.

Ultralight sleeping bags

Western Mountaineering Summerlite 

Western Mountaineering Summerlite - Ultralight sleeping bags

Weight: 1 lb. 3 oz.

Dimensions: size: 5’6″ – 6’0″ – 6’6″; inside girth (shoulder/hip/feet): 59″/51″/38″, 60″/52″/38″

Price: 420$

Temperature rating: 32°F

Cons: quite expensive, a little tight, not great waterproofness

Pros: versatile, good fabric

This full hood bag has a nylon ripstop fabric, a 850+ goose down filling of 10 oz, and a respectable warm rating for three-seasons use. In our autumn jaunts in the countryside it kept us warm, even very warm, at 32°-30°F. Without wind, we had even to open the zipper to vent sometimes. A good deal of the warmth is due to its baffles, continuous, creating a deep layer of down without leaving cold spots. Also, it has tight design, eliminating empty space.

However warm, we wouldn’t suggest it for 20°F: it simply isn’t thick enough. In terms of lightweight, it’s pretty good, with just 1 lb. 3 oz, and yet, there are lighter models, of 8-10 oz. The experience of sleeping in it was positive for us, for the internal fabric is smooth and welcoming. But in a general way, the bag is a bit tight, and you can’t make big bustles inside. It’s impossible to keep big objets with you during the night.

The ripstop fabric repels little quantities of water, but when you pour the water of a bottle on it, it starts to wet. So, it’s better not to leave it under the rain. It’s versatile anyway, for it can stand from the beginnings of spring to the closure of autumn, while on summer you can sleep with an open zipper. With a packed size of 6″ x 12″, is really easy to place in a backpack, and takes a little place. Yet it has a certain cost, of more than 400$.

 Big Agnes Pluton UL 40

Big Agnes Pluton UL 40 - Ultralight sleeping bags

Weight:  1 lb.

Dimensions: height 6′, 6’6″; girth shldr/hip: 59 inches, 53 inches

Price: 370$

Temperature rating: 40˚F

Cons: quite tight, zipper to handle with both hands and fragile, minimalist hood

Pros: full-length zipper, allows venting

With the Big Agnes Pluton UL 40 we deal with a bag for three-season use, that won’t keep up with frost. It has a ripstop nylon shell and lining, and a 850-fill-power DownTek down. This down is water-repellent, able to resist little drops of water. The shell also withstands some little rain, but when the precipitations become moderate it lets water in. On the other hand, thanks to a full-length zipper, it can open and work as a quilt or blanket in summer.

We like the warmth and insulation of this bag, but it’s quite tight. People with a robust build could have very little room to move inside. This is normal, for the bag sacrifices space to reduce the weight. Also, the hood is minimalist, and has no real shape to adapt to one’s face. The cinch cord tightens and closes the hood, but without ergonomics. Yet, we slept anyway in it, and well, up to the temperature rating. For lower temperatures, it’s better to use another bag.

The zipper is a little awkward to use, for you have to use one hand to block the fabric around and the other to handle the zipper itself. The Big Agnes Pluton UL 40 is finally, a winner for its reduced weight and size, but also unfit for winter, and with a limited inside space. For sure there is no room to keep shoes or clothes inside. Check well your shoulder girth before buying it, or you should find yourself “packed” while resting.

 Western Mountaineering Flylite

Western Mountaineering Flylite -Ultralight sleeping bags

Weight: 14.3 oz.

Dimensions: length regular 6″ – long 6’6″; girth 59″ shoulder / 51″ hip / 39″ footbox

Price: 425$

Temperature rating: 36°F 

Cons: unable to withstand frost, the zipper is half-length and cannot vent too much

Pros: very light and portable

The Western Mountaineering Flylite is very interesting for its reduced weight and stuff size. It has a quite thin shell of nylon fabric and a 850+ fill goose down filling of 7.7 oz. The entire bag weighs less than a pound, even with its stuff sack, positioning itself among the best ultralight sleeping bags. When carrying it it in the backpack for some spring hikes we almost didn’t notice it, and for its stuffed size, it seemed almost a little portable stove.

The aspect of warmth is different. The bag has a fully-baffled structure, avoiding cold spot and enhancing insulation. The hood is abundant and the draft collar effective in stopping unwanted draughts from entering. However in summer it’s quite warm, and the half-length zipper cannot allow a complete venting. It’s great for the good season and not-so-warm spring and autumn, but definitely not for freezing temperatures.

Avoid using it before the the 15th of March and after the 15th of September on mountain zones, for with a temperature drop you could have a sleepless night. Sadly, despite its qualities, it’s not very waterproof and can get quite easily wet. Surely mountain runners, orienteers and people who want to travel light and fast can appreciate such a bag. Alpinists who intend to sleep in the safety of an alpine shelter can use it to keep their packsack lightweight.

 Feathered Friends Hummingbird UL 30

Feathered Friends Hummingbird UL 30 - Ultralight sleeping bags

Weight:  1.33 – 1.45 lbs.

Dimensions: length 6′ 0″- 6’6″; girth 58″ shoulder / 52″ hip / 38″ footbox

Price: 509$

Temperature rating: 30 F

Cons: narrow design, not waterproof

Pros: great lightness and insulation, can unzip and become a quilt

Beside being very lightweight and compact, the Hummingbird UL 30 has a great thermal insulation for its rating. Its outer shell is in Pertex Endurance, with a 10 denier, and a filling of 12 oz. in 950+ goose down, which is amongst the highest values we could find. The bag kept us warm, and more, in some autumn hikes in the alpine regions of France; we dare to say it could be also insulate very well at 25°F, but we didn’t try that.

There is a full-length zipper, strong and snag-resistant, that can open and basically turn this model in a quilt. So in summer it can serve without toasting the body. On the comfort side, the bag is narrow, so much that we would suggest to measure your shoulder girth before buying it, for if you are quite muscular you could feel the bag compressing your chest. In this case, look for some wider (and sadly heavier) bag.

Another problem to note is that it’s not waterproof, and even a light rain will start to penetrate it. But, with 7.3 liters of stuffed size, we love to put it in an angle of the backpack without worrying about the volume of all our gear. Finally, it’s a great bag with serious quality materials, but remember it’s also very adjusted to the body shape. Those who want to spend long periods of time camping and move freely and widely in a bag, should look for another one.

 Sea to Summit Spark 40

Sea to Summit Spark 40 - Ultralight sleeping bags

Weight: 12 oz.

Dimensions: fits up to 72, 76 inches

Price: 339$

Temperature rating:

Cons: just for summer use, tight

Pros: excellent packability, ultralight

The Sea to Summit Spark 40 is insanely light and packable, and a good companion for summer hiking and mountain running. With a shell fabric in 70D nylon and a 6.3 oz of 850+ goose down filling, it has a stuffed size of 4″ x 7″. It’s one of the lightest bag we can find, and ideal for walking around and running with a backpack. In its stuff sack, it makes almost the size of a liter water bottle: incredible for a sleeping bag.

On the other hand its correct temperature rating is of 40°F, and cannot go lower. This bag is for two-season use, for in the coldest periods of spring and autumn the insulation isn’t enough to cope, and there are cold spots between the baffles. This model sacrifices insulation and features to gain lightness, so consider using it just in summer or for desert trips. Its ability to vent is also relative, because the zipper is half-size.

So the bag cannot transform into a quilt. There is neither a draft tube or collar. The general structure is very simple, but not windproof or waterproof. The real cool thing is that can fit almost anywhere, and is barely noticeable for its weight. This model comes in different variations to withstand colder temperatures, but in these cases the weight will increase. In the end, the Sea to Summit Spark 40 is a choice for summer activities.

Zpacks Classic 20°F

Zpacks Classic 20°F

Weight: 20.3 oz

Dimensions: length 5’6″ – 6′ 0″ – 6’6″; girth 61″ shoulder / 61″ hip / 35″ footbox

Price: 429$

Temperature rating: 20°F

Cons: no hood or draft collar, small footbox, cannot open as a quilt

Pros: very warm and light, decent waterproofness

As a warm hoodless mummy bag, the Zpacks Classic is an appropriate three-seasons bag, with a Ventum Ripstop Nylon outer shell. Thankfully this tissue got a DWR, and so can repel little quantities of water and rain. The filling material consists of 13.1 oz 900 down-fill, with a respectable and realistic temperature rating of 20°F, and a mild water-repellence. In our outings in the American countrysides we verified this bag keeps its warmth above freezing.

Yet there are no draft collar (a bungee cord tightens around the neck) or hood, and at some point we had to put on a hat, or sleep with our hood jacket to avoid catching too cold. The box baffles structure is thick and stops the cold air from sneaking in. The quality of sleep in it is satisfactory, but the footbox is a little narrow, and the cord to close around the neck is quite long and wanders around during the night. The zipper however is only half-length.

Then the bag cannot open to vent completely or become a quilt, and in summer you may experience too much warmth. In its stuff sack it sizes 6″ x 12″, leaving a lot of free place for other stuff in the packsack. We think it’s a very good bag for moving in the countryside and mountains from the late spring to the early autumn, while keeping the weight low. It’s serious gear, and you should like it, if you’re ok to remain without an integrated hood.

Marmot Micron 40 – Ultralight sleeping bags

Marmot Micron 40

Weight: 1 lb. 6 oz.

Dimensions: length 6′ 0″; girth 60″ shoulder / 55″ hip / 40″ footbox

Price: 179$

Temperature rating: 46˚F

Pros: very affordable, can open to become a quilt

Cons: heavy for its temperature rating, not windproof

The Marmot Micron 40 catches our attention for being very lightweight, of good manufacture and coming at an interesting price. It has a nylon outer shell and a filling of 9 oz. of 650 down-fill, also hydrophobic. Furthermore, it has a good deal of features for serious three-seasons activities as hunting or hiking. But the interesting thing is that it comes for a price well below the average of other ultralight sleeping bags.

The bag is comfortable, the hood spacey and closes smoothly around the face. When the temperature goes up the full-length zipper can open and transform the Micron 40 into a quilt, and serve also for your spouse or partner. The lining doesn’t scratch the skin when sleeping in underwear, and fits ok. The down filling isn’t of superior quality, and other bags with better down are even lighter. Yet, for 179$, the Micron 40 is a good deal.

With a stuffed volume of 3.9 liters and an internal pouch, this bag can suit very well bike-packers and backpackers in spring, summer and autumn, while temperatures are moderate. On the other hand, it has not resistance to wind, so cold drafts can make you wake up at night, and its impermeability is limited to the down. It cannot neither be united to a twin model to create a double bag. But it can be an interesting bag for occasional users.

Sierra Designs Cloud 800

Sierra Designs Cloud 800

Weight: 22.3 oz

Dimensions: length 6′ 0″ – 6’6″; girth 62″ shoulder / 60″ hip / 42″ footbox

Price: 350$

Temperature rating: 35°F

Pros: zipperless system, foot vent, roomy for an ultralight model, good comfort

Cons: cannot close as a zipper bag, not waterproof, not for side sleepers

The Sierra Designs Cloud 800 aroused our interest for being not just very portable, but also for a generous foot vent to use when you’re getting too warm. It’s a bag to use just in the good season, when you have sunny days and warm nights, and you could stay even outside a tent. It has a 10.4 oz filling of 800 down, and an uncommon design. In fact, it has no zipper, but a front comforter folding itself into the side of the bag.

The open comforter

All ultralight sleeping bags tend to be narrow, but the Cloud 800 is the exception, for this open comforter is flexible and allows more room for people with large shoulders. This comforter, on the right, arrives to touch the left shoulder. Anyway, on one side it cannot open to convert in a quilt, but in summer it’s really easy to put the feet outside of the foot vent and cool down. In sum, it’s a bag for people who want to move and stretch their legs during sleep.

Weighting 22.3 oz and with a stuff size of 7″ x 13″, it’s an interesting option for camping and travelling from spring to autumn. But if you have the habit of side sleeping, drafts will eventually enter through the comforter. This could be annoying. This bags is mostly for back sleepers, and to use on a pad, because on the back there is a panel without down inside. This is meant to let the filling remain on the front, where it’s more important.

Feathered Friends Flicker 40 UL – Ultralight sleeping bags

Feathered Friends Flicker 40 UL

Weight:  19.1 oz

Dimensions: length 6′ 0″ – 6’6″; girth 62″ shoulder / 48″ hip / 39″ footbox

Price: 429$

Temperature rating: 40°F

Pros: versatility, can open in a quilt, waterproof

Cons: no hood, not for winter

While on a first sight the Flicker 40 UL appears as common hoodless bag, the truth behind is quite different. This model unites lightweight, versatility and waterproofness, and is practically a sleeping bag and a quilt at the same time. The shell fabric is in Pertex Endurance, naturally water-resistant and breathable, and the 8.4 oz filling in 950+ insulates effectively while keeping the weight low. The result is a bag very performing for the warm season.

With horizontal baffles, no dead spots are present to allow drafts in, and the sleep is more than snug from spring to autumn. A neck collar closes above the shoulders to avoid cold air from entering, but there isn’t a hood to cover the head. It’s enough to keep you always cozy, except in winter, and this bag should not be used in freezing nights. On the contrary, in hot summer nights it can open completely through the zipper and become a quilt, or blanket.

A drawcord at the bottom of the bag can create a footbox to insulate even more the feet when the thermometer goes too low. We used the bag in rainy conditions and it remained dry for many days, with our satisfaction. It makes a size of 7″ x 10″ in the stuff sack, the size In conclusion, the Flicker 40 UL is a gear for fast travellers, hikers and hunters who want to minimise the weight and stuff size of their bags during the good season.

Rab Mythic Ultra 180 – Ultralight sleeping bags

Rab Mythic Ultra 180

Weight: 14.1 ounces

Dimensions: length 6′ 0″ – 6’6″; girth 63″ shoulder / 52″ hip

Price: 550$

Temperature rating: 32°F

Pros: excellent waterproofness, warmth-to-weight ratio and insulation

Cons: short zipper, limited venting, expensive

The Rab Mythic Ultra is atypical in its conception and materials, and yet excellent. While ultralight, not arriving even to a pound, it enhances heat preservation and impermeability. The outer shell in ripstop nylon incorporates titanium in the fabric via the Thermo Ionic Lining Technology (TILT), reflecting heat toward the sleeper. This allows to get a strong insulation while reducing the need for a thick, heavy filling.

However, also the 900+ fill-power goose down is hydrophobic, with a Nikwax fluorocarbon-free finish. So this bag is pretty waterproof and warm, to the limit of winter time. It’s great for sleeping in autumn conditions, even in rainy days. We were quite curious to test it for this titanium technology, and slept in a comfortable cocoon without feeling cold or drafts, safe in a big hood cinchable around the face. And the down accumulates no humidity.

However, the zipper is short, arriving to open to our elbows. We never had problem to enter and exit the bag, but it cannot assure a great venting. For sure the Rab Mythic Ultra stands among the lightest and most packable (6″ x 8″ stuff size) sleeping bags of the present day, and can be extremely useful for fast travellers avid to have a warm bed for resting, and keep it as little as they can, or to have it as an emergency bag.


We made a review of some if the best ultralight sleeping bags we can find around. They are much more portable than summer, camping, double and normal backpacking bags. Their main advantage is their lightness, but for sure they are also a little tight, and sometimes their fabric is very thin (again, to reduce the burden). If you want a roomier, warmer and more resistant model, you can check our other pages on cold weather or winter sleeping bags.

As you noticed, they have all down filling, for down is the only material allowing to reduce weight to this point, especially high-quality down. We didn’t include synthetic filling bags in this page, for they start immediately to weigh more and add at least a few ounces to the final result. This may not seem much, but we know people looking really at gear coming at less than 16 ounces. Perhaps in a near future we will add some synthetic model to the list, after properly testing them.

Diamond sleeping bags