Backpacking has advanced a lot in the last few decades. Gone are the days of cumbersome tents and heavy sleeping bags. Now, you can choose between a variety of options that knock ounces off of their predecessor’s weight. If you want to backpack without hauling in extra weight, it’s time to get the best ultralight sleeping bag.
Ultralight sleeping bags don’t take up much room in your pack and add minimal weight to your overall setup. They’re also comfortable enough for use in a tent, hammock, or just on a sleeping pad if you want to bivy under the stars.
In this guide, I’ll review the best ultralight sleeping bags and explain how to find one that fits your outdoor aspirations.
My Review Process
I’ve been hiking and camping since I could walk. In that time, I’ve tried dozens of sleeping bags on various trips. After some memorable experiences, both good and bad, I decided to dive into the best ultralight options on the market.
When considering an ultralight sleeping bag, I prioritize a few qualities. I always look for overall weight, temperature range, materials used, packability, and water resistance rating. Things happen in nature, and the last thing you want is a cold, wet sleeping bag that takes up too much room in your pack.
With those things in mind, let’s dive in. If a term appears that you’re unsure of, like baffles, scroll down to our buying guide, where an explanation awaits!
My choice for the best-overall ultra-light sleeping bag is the Therm-a-Rest Hyperions 20F. This stellar bag weighs next to nothing at about 20 ounces and is stuffed with 900 fill dry-down feather insulation for extra comfort. The sleeping bag is also supremely packable, compressing down to 3.5 liters.
The mummy design, along with the hood, does limit movement inside the bag. Tossers and turners may find the snug fit to be restricting. Additionally, the insulation is filled 70% on the top and 30% on the bottom. This means that thermal efficiency is best achieved by sleeping on your back, which may irk side sleepers.
However, another glowing positive is the warmth-to-weight ratio. The ratio is calculated using factors like the type of fibers used, material thickness, and insulating power. For down fill (the down feathers of waterfowl), the higher the number, the better it is. Weighing only 20 ounces and stuffed with high-quality 900-fill down, the Hyperion is at the top of the heap.
If you’re looking for one of the lightest, comfiest, and most compressible sleeping bags out there, the Therm-a-rest Hyperion is for you.
If you’re new to backpacking quilts, I recommend the Zpacks Classic 20F. This hybrid design features a ¾ zipper, leaving you a large enclosed foot box to keep cold feet warm. Ultralight quilts are supremely light, and the Zpacks 20F weighs in at just over 18 ounces. The 950 down fill is also very comfortable and compressible.
Backpacking quilts are hoodless sleeping bags, which may be an issue on colder nights. Additionally, for those who have used quilts before, the Zpacks Classic doesn't have a full-length zipper. While this helps keep warmth in the foot box, it’s also less versatile than full-length zipper quilts.
However, at 18 ounces, this is a true ultralight sleeping bag. It's perfect for warmer nights under the stars. If you’re unsure of the advantages of backpacking quilts, see the section below the reviews for a brief comparison.
If you’re hiking for a few days and with variable temperatures, I highly recommend the Western Mountaineering Summerlite. The sleeping bag features high-quality construction, a great warmth-retaining mummy hood, and only weighs 19 ounces.
The Western Mountaineering Summerlite gets its excellent warmth from 4 inches of down between its two fabric layers and by reducing the fit. This snug style of the sleeping bag holds warmth but eliminates the ability to move around. Side sleepers and restless sleepers may find the narrow dimensions a little too tight for their liking.
However, this sleeping bag is perfect for warming up after a long day on the trail. The Western Mountaineering Summerlite's snug fit and mummy-style hood will keep you comfy from spring to early winter.
Feathered Friends are a venerated player in the ultralight sleeping bag department. The Hummingbird YF 20 is easily my pick for the best backpacking bag. Boasting a weight of 20.5 ounces and a superb warmth-to-weight ratio, the quality of this 3-season sleeping bag is an immediate highlight. The bag is also abrasion resistant, which adds to its backpacking appeal.
The biggest downside to this bag only reveals itself after extended use. The bag uses continuous horizontal baffles. Baffles are the compartments in the sleeping bag that hold the down feathers. If they are continuous, the down feathers can clump in certain areas. When this happens, you have to spend time redistributing, or you’ll end up with cold spots.
However, if you need a warm, high-quality ultralight sleeping bag for long trails, the Feathered Friends Hummingbird YF 20 is for you.
Mountaineers encounter all sorts of crazy conditions out there, and they need a sleeping bag that can keep up. My choice for the best ultralight mountaineering bag is the RAB Neutrino 900. This down-insulated bag can handle moderate winter conditions, has a fantastic warmth-to-weight ratio, and weighs ~2.85 lbs.
While this stellar option can handle a wide range of temperatures, it’s not rated for extreme weather. There are better options for very warm nights or frigid temperatures. The weight is also fine but not a leader in the ultralight department. If you’re counting ounces, that’s worth mentioning.
Overall, the RAB Neutrino 900’s combination of warmth, weight, and compressibility easily hold up to the demands of mountaineering.
Double sleeping bags are great for getting loved ones out into the wilderness. At their best, they are warm, comfortable, lightweight, and can handle a variety of conditions. The Big Agnes King Solomon does all of that and is my pick for the best ultralight sleeping bag.
In order for this bag to work, you must attach it to an insulated sleeping pad. The way that King Solomon reduces weight is by taking it off the bottom of the bag. That means, without an insulated sleeping pad, you’ll get a lot of heat loss out of the bottom. With one, it's amazing, but you have to buy it separately.
Coupled with a sleeping pad, this is a phenomenally designed sleeping bag. It can sleep two comfortably, packs down well, weighs around 5 lbs, and is stuffed with effective down feathers for thermal efficiency.
Like other mummy-style bags on this list, the Rab Mythic Ultra 360 is lightweight and very warm. It’s my choice for the best ultralight mummy sleeping bag due to its ergonomic shape and extra warmth for cold sleepers. This design style, the 900 fill down and included hood make it a warmth retention winner.
Due to the design style of mummy sleeping bags, people may find it a bit restricting. Side-sleepers and restless sleepers may not enjoy the constricting feel. However, if you need to stay warm and cozy, it’s hard to beat the Rab Mythic Ultra 360.
While the 900 down fill is awesome on its own, Rab takes it one step further. They employ their own Thermo Ionic Lining technology, which is applied to the lining of the bag. It effectively bounces back your body heat which increases thermal efficiency for snug sleeping.
If you have to deal with snow and cold weather on an outdoor adventure, the Snowbunting EX 0 should be your go-to. This impressively warm bag is also coated with heavy-duty durable water repellent (DWR) which is great when dealing with cold winter weather or melting snow. While it's not the lightest bag on the list, it’s the only one worth taking out in the middle of winter.
The Snowbunting Ex 0 has a small hood and is slightly heavier than other models. This snug sleeping bag is designed to keep precious body heat circulating by minimizing air space but might be too tight for larger folks. Take a look at our best winter sleeping bags article for more comparable options.
The bottom line here is if you’re hiking into wintry cold weather and want to remain ultralight, bring this bag with you. The exceptional warmth, comfort, and weather resistance more than makeup for the small downsides.
Not only is the Sea to Summit Spark 40F the best ultralight summer sleeping bag, but it’s also the lightest sleeping bag I tested. Coming in at only 12.4 ounces and featuring enough packability to shrink down to the size of a Nalgene, this is one versatile sleeping bag. The down feathers are also treated with Hyperdry down water repellent, so they'll still insulate when wet.
Because of the bag's ultralight design, you really don’t want to use it if night temperatures dip toward freezing. The included hood and down help you stay relatively warm, but for shoulder season adventures, I’d recommend extra layers or something warmer.
However, for warmer nights and summer adventures, nothing can beat the Sea to Summit Spark 40Fs ultralight 12.4 ounces of weight.
The Kelty Cosmic 20F Sleeping Bag proves you can get great value at a fraction of the price of other models. Filled with down and featuring an adjustable hood and draft collar, the Kelty Cosmic has a lot to offer. It’s also compressible, packing down nicely for easy transportation.
While it’s far from heavy, the weight of the sleeping bag is below what the lightest options in this list can give you. However, I can forgive a few extra ounces for the bargain price.
If you need a cheaper, ultralight sleeping bag for spring, summer, and fall, the Kelty Cosmic 20F is a very good option.
Quilt vs. Sleeping Bags
Ultralight sleeping bags strip away the extra insulation of a regular sleeping bag and focus on feathery materials and a “mummy” design to retain heat. The “mummy” style holds your body in place, and with a hood, keeps warmth circulating. This style is a bit restrictive and isn’t always roomy enough for restless sleepers.
Ultralight backpacking quilts take the lightweight concept a step further. Usually, ultralight quilts remove the bottom insulation, the hood, and the mummy design. What you’re left with is an insulated top sheet that can strap down around a sleeping pad, which will then act as your bottom insulation.
One downside with backpacking quilts is that they do not handle cold weather well.
Sleeping Bag Buying Guide
There are many ultralight and lightweight sleeping bags out there. Some have a temperature rating for warm nights only, while others perform reliably as 3-season sleeping bags.
If you want a backpacking sleeping bag that can handle a range of temperatures while retaining adequate insulation ability, read our buying guide below.
Ultralight sleeping bags can cost a lot of money. Higher-end models can cost anywhere from $500-800. On the other end of the spectrum, you can find a quality ultralight bag for about $150-400.
Weight, Comfort, And Temperature
It’s generally accepted that 2 lbs. is the upper limit for single-capacity ultralight sleeping bags. Most of our sleeping bags fall in this category, with some only a few ounces over 2 lbs. The heaviest model showcased is the double-wide King Solomon.
Ultralight sleeping bags aren’t meant for very cold nights. They work in a wide range of temperatures, from warmer nights down to about the freezing mark. A bag with a limit rating of 20 degrees can work down to 20 degrees, but comfort starts to slip well before then.
I recommend checking if the bag comes with a comfort rating, which is a much better assessment of temperature ranges.
The warmth-to-weight ratio calculates warmth in relation to weight. For example, a bag that uses 900 fill down and only weighs about 20 ounces has a very high warmth-to-weight ratio. A bag using 650 fill down and weighing 3 lbs. has a worse warmth-to-weight ratio.
A higher warmth-to-weight ratio provides a better, warmer bang for your buck.
Down Fill And Synthetic Fill
Down feathers are a layer of fine feathers found on waterfowl like ducks. They are incredibly soft and lightweight. Down feather insulation is synonymous with higher quality, comfort, and loft (the ability to trap warm air). However, unless the down fill is hydrophobic, water damage will negate its insulation ability.
When analyzing down-filled sleeping bags, you’ll see phrases like 900 down fill. The higher the number, the more down is stuffed into one cubic inch. So, higher fill numbers are better quality and have better insulation ability.
Synthetic insulation is cheaper and continues to insulate if you have a wet sleeping bag. However, it weighs more than down. If you’re just getting into the lightweight and ultralight field, starting with synthetic insulation is a great move. With synthetic insulation, you trade a bit of weight for reliable performance and better weather resistance.
Down and synthetic fill are held in place by a baffle. There are horizontal baffles, vertical baffles, and continuous baffles. Baffles are made in two ways, stitch-through, and box (also called continuous baffles).
Stitch-through baffling separates each baffle by an area of stitching. This design keeps the down feathers within each baffle, eliminating clumping. However, each stitched area isn't insulated and can let cold air in.
A box baffle design allows down to flow through the sleeping bag, meaning it has superior insulating ability. However, after a lot of use, the down might clump in certain areas. If you don't de-clump, areas not covered by down will become cold spots.
Insulated baffles come horizontally or vertically. In horizontal baffles, the number of cold spots in the stitching can be noticeable, especially on cold nights. Vertical baffles run the length of the sleeping bag and provide more continuous insulation from head to toe. However, each baffle is longer, which means you could get clumping anyway.
The rule of thumb for horizontal baffles and vertical baffles is to go for a higher fill number. The more down feathers stuffed into each baffle, the less likely you'll get clumping or cold spots. High-end bags also come with an insulated collar created through neck baffles.
Materials And Features
The outer fabrics of sleeping bags are made from nylon, polyester, or a combination of both. These materials are often coated with DWR (durable water repellent) for water resistance. Sometimes nylon ripstop is included, which adds abrasion resistance.
Higher-end sleeping bags and quilts use premium materials and come with additional features. Some that I like include a pocket for quick phone access, along with draft tubes. A draft tube is an insulated chamber that runs along the zipper track. Without one, full-length zippers create one very long cold spot down the side of your bag.
Your Sleep System
Weight savings in lightweight sleeping bags means you need to use additional equipment to complete your system. These include items like the best sleeping pads to reduce heat loss transfer and the best tents to stop the wind. On top of that, personal touches like the best backpacking pillows could also play a part.
Your sleep system is unique to you and your sleeping habits. The important part is to remember that a sleeping bag is part of that system, not the whole thing.
People who love the hooded mummy style will enjoy the Western Mountaineering Summerlite. And, if you're looking for the lightest sleeping bag out there, the 12.4-ounce Sea to Summit Spark 40F is a winner.
*The information on this site is based on research and first-hand experience but should not be treated as medical advice. Before beginning any new activity, we recommend consulting with a physician, nutritionist or other relevant professional healthcare provider.