Best Ultralight Sleeping Bag of 2020 | Expert Advice

If you quickly want to find out which is the best ultralight sleeping bag, I’d recommend the Therm-a-Rest Questar Sleeping Bag.

Going for an ultralight sleeping bag is a great start to cut down pack weight, as they are one of the heaviest items in your backpack.

That’s not all..

The comfort, weight-to-warmth ratio, temperature ratings, insulation, fit of the bag, etc also need to be considered.

In this guide, you can find some of the best ultralight sleeping bag reviews, and some solid buying advice. Keep reading!

Our Top 5 Ultralight Sleeping Bags of 2020


Therm-a-Rest Questar 20-Degree Lightweight Down Mummy Sleeping Bag

Weighs 2.4 lbs

1. Therm-a-Rest Questar Sleeping Bag

  • Great packed size; comes a stuff sack and a mesh storage bag
  • Has loops on the back of the bag that you can strap to camping mattress
  • Has an additional zipper at the bottom

Weighs 1.13 lbs

2. Western Mountaineering Sleeping Bag

  • Best for Lightweight Quality & Warmth
  • Comes with a full length zipper
  • Durable and water resistant

Weighs 2.8 lbs

3. Kelty Cosmic Sleeping Bag

  • Best budget buy
  • Warmest among other sleeping bags in its price range
  • Comes with an impressive set of accessories such as footbox, electronics holder, etc.

Weighs 2 lbs

4. KLYMIT Down Sleeping Bag

  • Keeps you snug and toasty warm down to 20F
  • Has a 3/4 zip design with two way sliders for easy mobility
  • Has a water resistant coating on the outer fabric

Weighs 1.25 lbs

5. Marmot Phase Down Sleeping Bag

  • Best for Weight-to-warmth ratio
  • Good packed volume
  • Comes with a footbox that does not suffocate your legs

We've created a comprehensive Ultralight Sleeping Bags buying guide along with the types of sleeping bags. 

What can you expect in this article?

We have chosen some of the best ultralight sleeping bags for you to choose from, based on some of these key distinguishing features:

  • Price
  • Weight & Comfort
  • Temperature Rating
  • Water Resistance
  • Safety & Warmth

Types of Sleeping Bags

Sleeping bags majorly fall into the below two categories.

Mummy Bags

Mummy Bags, as the name suggests encloses you tightly like a mummy, without much space left for anything else. It can be quite cozy but the less space can also leave you feeling cramped.

They come with and without hoods, are wider at the top, and narrower the the bottom thus encapsulating you completely.

Mummy bags are generally preferred when the temperature is below freezing.

Are you a cozy sleeper? Go for Mummy bags.


If you feel Mummy bags could be constricting and suffocating because of the space, quilts should be your choice. They allow for a little more space in the bag for you to move around.

Quilts don’t come with hoods so you might want to consider an alternative for it.

Quilts are popular because of the ratio between weight to warmth it provides. The sleeping pads that are attached to the quilts keep you warm.

Quilts are preferred when the temperature is above freezing.

Key Distinguishing Features


Sleeping bags would be one of the expensive items in your backpacking list.

Particularly, if you prefer ultralight options, the price tends to be higher than the normal because it’s made of high quality fabrics to make it ultralight.

People who go backpacking very often, have 2-3 bags that suit for different weather conditions. In that cases, it is best to invest in a good quality product ( $350 – $500 ).

If it’s not the case, you can go for the cheaper options. The good ones generally range between $250 and $500.

If you go for the cheaper options, they can still solve your purpose but with time, quality and durability of the product might become questionable.

Weight & Comfort

Who doesn’t like an ultralight sleeping bag that’s easy on the shoulders and warmer in the nights?

But there’s a catch.

When you are going ultralight, you might be compromising on something, be it’s warmth, comfort or safety.

Some products here, that are relatively not as ultralight & versatile as the others, make up for it in warmth & comfort.

Quick Tip – 2lbs or less is a good weight for an ultralight sleeping bag.

Temperature Rating

Every sleeping bag comes with a temperature rating that tells you which one to go for, under which conditions of weather.

Go for a bag that is warmer than you think it will be, the descriptions by the manufacturers is not accurate in most of the case.

What’s the real story?

The sleeping bags that come with a lower limit generally mean that you can survive the cold up to that, that means that you will be in for a sleepless cold night. However, you can get a ballpark estimate from it, as to how much of cold you will be able to sustain with the temperature rating of the bag.

For cold nights, it is recommended to go for a bag with 25-30 degrees Faranheit and 10-15 degrees for warmer needs.

Quick Tip – Women tend to be cold sleepers generally and men, the hot sleepers.

Water Resistance

There are no safe bets in this, since the claims about the sleeping bags being waterproof might not entirely prove true during a downpour.

Bags that come with a durable water repellent ( DWR ) coating, adds on a layer to the sleeping bag that caused water to bead up outside it, rather than soaking in.

The coating is usually done on the sleeping bag’s shell fabric, or the bags that are made with a naturally resistant shell fabric. You can rely on bags with this feature, when you need to prevent water getting absorbed because of the condensation in the tent.

DWR coating tends to wear off with time, but reapplying it is no big deal since it’s a nice feature to have in your sleeping bag.

Safety & Warmth

Safety should always be in the back of your mind when you choose to go for products that lighten your load. Be ensured that you’re not compromising on the weight or comfort.

If you predict extreme conditions in the hike, it is a good choice to be educated also about the Bivy sacks or the shelter plus sleep system.

Top 5 Best Ultralight Sleeping Bag Reviews

1. Therm-a-Rest Questar Sleeping Bag

Weight – 2.4 lbs

Temperature rating – 20F

Chosen for – Comfort, packable size and well thought-out features.

Down Fill Power – 650


  • It has a snug design that keeps you warm and comfortable.
  • The weight-to-warmth ratio is one of the best among the other products in the review. 
  • It comes with a stuff sack that has two strings for packing it perfectly. Bonus points for the additional mesh storage bag.
  • In addition to the top zipper, there is also a convenient bottom zipper to let in air when needed. 
  • Another well thought out feature is the loops at the back of the sleeping bag that you can strap your camping mattress/sleeping pad with. It ensures that the sleeping bag doesn't shift side at night.


  • The regular bag claims to fit people upto 6 feet but it can feel a little tight.

2. Western Mountaineering UltraLite 20 Degree

Weight – 1.13 lbs ( Size Regular )

Temperature rating – 20F

Chosen for – Weight, Warmth & Compressibility

Down Fill Power – 850+


  • This is the warmest 20F bags out of the lot that is reviewed here, and is suitable for 3 seasons.
  • Pull strings and adjustments around neck and head area are one of the many features that make this bag enticing. Comes with a full length zipper that’s very convenient to seal you within the bag.
  • It has an excellent compressed size.
  • It has a water resistant shell that protects you & the down insulation from condensation.
  • It also has a no catch zipper system that ensures its durability.
  • It’s long lasting and is durable for years on end. Invest in this bag and you won’t regret it!
  • The best ultralight sleeping bag in this review.


  • For people who are broad-shouldered, the shoulder width of the bag may be small. You can look at other variations of the same bag with bigger dimensions! One such alternative - Western Mountaineering AlpinLite.
  • For midsummers, it might be not the right choice as it can get warm.
  • It is expensive.

3. Kelty Cosmic 20 Degree Down Sleeping Bag

Weight – 2.8 lbs

Temperature rating – 20F

Chosen for – Best Budget Buy

Down Fill Power – 600


  • Provides the best warmth (20F) among the other sleeping bags in this price range.
  • It comes with a ⅓ length two way anti-snag zipper, making it comfortable to get in and out. Once zipped, it totally cocoons you giving you a very warm sleep.
  • Has impressive accessories such as the Footbox, Electronics Pocket and Thermal-comfort hood for comfort.
  • It has a super packed size, when put in the compression sack that it comes with. Great for those who have limited space on their backpack.
  • Comes with a variety of lengths - Short, Regular, Women's Regular and Long.


  • Bulkiest of the bags in the review. Chosen as the best budget buy with considerably less weight and good performance and comfort.

4. KLYMIT Down Sleeping Bag

Weight – 2 lbs

Temperature rating – 20F

Chosen for – Price and fluffy comfortness

Down Fill Power – 650+


  • It is one of the warmest bags in our review. It fluffs up real quick, along with the baffles and innovative hood design that keeps it toasty warm and breathable.
  • It has a 3/4 zip design with two way sliders for easy mobility. 
  • The inner side of the sleeping bag is made of silky soft Nylon material that gives super comfort.
  • It has thoughtful features such as a broad chest area, a convenient footbox and a stash pocket to store handy stuff.
  • It comes with a DWR ( Durable water Repellent ) coating on its outer shell.


  • It’s a little heavier in comparison to the other bags, but fits the bill.
  • It also has a low down fill power that makes it a little less compressible while packing.

5. Marmot Phase 30F Degree Down Sleeping Bag

Weight – 1.25 lbs

Temperature rating – 30F

Chosen for – Weight-to-Warmth ratio

Down Fill Power – 850+


  • Extremely lightweight & warm - the most ultralight bag in the reviews here. It is made with premium materials like ultralight pertex quantum, that gives it a very good weight-to-warmth ratio.
  • Very easily compressible - has an excellent packed volume.
  • It has a silky soft touch to it, that is one of the most endearing features of the bag.
  • It has a fantastic hood design, a multi-baffle one that does a neat job at trapping the heat.
  • It comes with a vaulted foot box, that increased the insulation near your feet, and keeps you warmer. It also makes some room for your feet to move around.
  • Deemed best for backpacking & summer mountaineering seasons.


  • The only disappointing thing about the bag is the side zipper, which catches at times.
  • Some feel that it has tight internal dimensions.
  • It is not as warm as a 30F bag should be.

Quick Tip - The same bag also comes at a 20F temperature rating specification, for those who are looking at a lower range. Here’s the LINK.


Our pick for the best ultralight sleeping bag is the Therm-a-Rest Questar Sleeping Bag. It has has an excellent weight-to-warmth ratio, a great packed size and is also priced reasonably.

It has water-resistant technology implanted in it. Things that stand out in this bag are the well thought out features. Be it the down zipper that you can use when you feel like your feet need some air, or the loops at the back of the bag that you can loop to the mattress, the bag definitely is a winner. It keeps you warm and snug, thanks to its mummy style design. 

We hope this guide justified finding the best sleeping bag to fit your needs. Thanks for reading and happy hiking!

Let us know which one you picked in the comments.

Related: The Best Lightweight Sleeping Bag of 2020.

Mark Bennett

I have a serious thing for travel, outdoors and wilderness. I grew up in Oregon and camping outdoors with my father was one of the fondest memories of childhood. I enjoy camping and hiking and love to share what I've learnt over these years.