Updated on January 9, 2022

A good sleeping bag is essential to ensure that you get your well-deserved sleep during your adventures – whether it’s a trip through South America, a trek in the Himalayas or a bike ride along the Balkan coast. The best mummy sleeping bags offer maximum protection from the cold while occupying the minimum amount of space when packed down.

Today, brands have developed new technologies to create extremely light and compact products, offering great comfort even at the lower temperatures. We have selected the five best mummy sleeping bags for every season, so you can go hiking anywhere without worrying about nighttime comfort.

For a complete analysis of all backpacking sleeping bags, check out the buyer’s guide Best Backpacking Sleeping Bags.


Quick Answer - The Best Mummy Sleeping Bags

  1. Big Agnes Sidewinder SL 20
  2. Marmot Sawtooth 15
  3. Kelty Cosmic 20
  4. Therm-a-Rest Hyperion 20
  5. Marmot NanoWave 45


Comparison Table - Best Mummy Sleeping Bag

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NameInsulationTemp RatingWeightPriceRatingReview
Big Agnes Sidewinder SL 20D-S Blend20 F2.2 lbs$2804.7Read Review
Marmot Sawtooth 15Down27 F2.5 lbs$2794.4Read Review
Kelty Cosmic 20Down32 F2.6 lbs$1704.3Read Review
Therm-a-Rest Hyperion 20Down32 F1.2 lbs$4004.2Read Review
Marmot NanoWave 45Synthetic56 F1.8 lbs$794.2Read Review
NameInsulationTemp RatingWeightPriceRatingReview

Temp ratings refer to the EN or ISO Comfort rating.

Weight and price are shown for the regular size.

Want to learn more about a technical term? Check out our Features Explained section below.

Need buying advice? Take a look at these Things to Consider.

Reviews - The Best Mummy Sleeping Bags for Backpacking

Big Agnes Sidewinder SL 20

View Women's Version
  • Fill Weight: 19.0 oz
  • Insulation: D-S Blend
  • Weight: 2.2 lbs
  • Volume: 04.3 L
  • Temp Rating: 20 F
  • Fill Power: 650
  • Body-mapped FireLine™ ECO synthetic insulation
  • Made from post-consumer recycled polyester
  • Includes storage sack and stuff sack
Big Agnes Sidewinder SL 20 Backpacking Sleeping Bag


The Big Agnes Sidewinder SL20 is spacious enough to be a game changer for side sleepers but it doesn’t trap cold air as much as other wide options.

What we love the most about the Sidewinder SL20 is that it’s one of the only bags on this list that is truly built for side sleepers. The zipper and the hood face the side. The insulation and shape are all geared toward those who roll over. There is a mesh pocket for your pillow that keeps it in place. There is extra padding at the hip and feet, which are two pressure points for those who tend to flip from side-to-side several times throughout the night. There is plenty of room to curl your knees up without feeling constricted as you might in a mummy bag. 

One complaint we have with this bag is the zipper catches if you aren’t careful despite having an “anti snag zipper”. Maybe we were too rough with it but this could be annoying if you have to get up in the middle of the night. Also, people with wide feet might find the toe box a bit tight. 

The Nemo Disco 15, which is also featured on this list is a close competitor to the Big Agnes Sidewinder SL 20. The Sidewinder gains points on weight (it’s 7 ounces lighter), but it is not as roomy as the Disco. The extra inches on the shoulders and hips are nice but you also have to consider that it’s not the best design for retaining warmth.

The Big Agnes Sidewinder SL 20 also comes in a women’s version.

Marmot Sawtooth 15

  • Fill Weight: 21.0 oz
  • Insulation: Down
  • Weight: 2.5 lbs
  • Shape: Mummy
  • Volume: 07.0 L
  • Temp Rating: 27 F
  • Fill Power: 650
  • Shell Material: 20-Denier Mini Ripstop Nylon
  • Warm
  • Comfortable
  • Internal Stash Pocket

The Marmot Sawtooth is a quality down sleeping bag that incorporates a healthy mix of warmth and water protection given the price. With a comfort rating of 27.1 degrees F, the Marmot Sawtooth will keep you warm on most 3-season backpacking trips. 

For peace of mind when moisture strikes, this down sleeping bag not only incorporates water-repellent down but a durable water-repellent shell as well. The drawcord collar is a nice touch to help cinch this bag down and block out the cold. Should you find temperatures to be colder than expected, stuff a heat packet into the heat pocket at the bottom of the bag and keep your toes nice and toasty.

Kelty Cosmic 20

View Women's Version
  • Fill Weight: 16.0 oz
  • Insulation: Down
  • Length: 72 inches
  • Weight: 2.6 lbs
  • Shape: Mummy
  • Volume: 09.2 L
  • Temp Rating: 32 F
  • Stuff Sack Size: 8 x 13 inches
  • Fill Power: 550
  • 550-fill down
  • C0 and PFC-free durable water repellent (DWR) coating
  • Internal zippered stash pocket
Kelty Cosmic 20

The Kelty Cosmic 20 is a budget minded down sleeping back that is a great option for new backpackers who don’t mind carrying a bit of extra weight and bulk to save some cash.

What we love the most about this bag is its overall value. The Cosmic’s quality and warmth are great considering how inexpensive it is. Of course, you can’t compare the build and material quality of the Cosmic to the top of the line bags on this list but it is practical and comfortable enough, making it tough competition for other budget options.

The biggest downside of the Cosmic is it is much more heavy and bulky than other backpacking sleeping bags, but hey, it’s one of the cheapest down bags around. If you’re just starting out, you could always go for the Cosmic and if you end up becoming a hiking junkie, you could upgrade and retire this bag to car camping adventures. 

This bag is also offered in 40-degree and 0-degree versions. 

The Kelty Cosmic 20 is also available as a women’s version

Therm-a-Rest Hyperion 20

  • Fill Weight: 12.0 oz
  • Insulation: Down
  • Weight: 1.2 lbs
  • Shape: Mummy
  • Volume: 03.0 L
  • Temp Rating: 32 F
  • Fill Power: 900
  • Lightweight And Small Packing Size
  • Ergonomic Shape And Long Zipper
  • Moisture Resistant Fabric

The Therm-a-Rest Hyperion 20 is a lightweight high quality bag that was designed to help long distance hikers shave pounds from their load.

What we love the most about this bag is its warmth to weight ratio. It’s filled with 900 down which makes it so warm and light. It also packs down quite small, making it great for saving room in your backpack. A little feature we liked was there are two straps underneath it which you can attach to your sleeping pads to keep the bag from slipping off. The Hyperion comes with a compression bag which helps get the bag down to about the size of a large water bottle. There is more insulation on top (70%) and less on the bottom (30%), this saves weight but it also means the design is optimized for sleeping on your back. 

What this bag gains in weight saving, it pays for in comfort. The cut is slim, very slim. So, if you’re a bigger dude or lady, you will probably feel constricted in this thing. The Hyperion is very narrow throughout and tapers down even more at the feet. The zipper only goes halfway down the bag, which does shave some ounces but it also means you can’t vent your feet. And, while we’re talking about the zipper, let’s just say it has some room for improvement. There’s a bit of fabric that runs along the zipper but it still snags from time to time. 

The Hyperion 20 is excellent value for money and is cheaper than other high end bags on this list, but it is lacking some features like a draft collar that lets you seal the bag around your face. Also, while it’s rated to 20 degrees, its comfort rating is 32 degrees. So we only recommend this  bag for above freezing conditions. If you’re the kind of hiker who doesn’t mind sacrificing some comfort in order to go fast and light, the Hyperion 20 could be the perfect bag for you. 

This bag also comes in a 32 degree version.

Marmot NanoWave 45

  • Fill Weight: 13.9 oz
  • Insulation: Synthetic
  • Length: 72”
  • Weight: 1.8 lbs
  • Shape: Mummy
  • Volume: 05.0 L
  • Temp Rating: 56 F
  • Stuff Sack Size: 6x11”
  • Fill Power: Spirafil
  • Snagless Draft Tube Keeps Cold Air From Seeping Through Zipper
  • Zipper Wraps Around Foot Box For Easy Ventilation
  • “Feely” Drawcords For Easy Adjustment Even In The Dark
  • Synthetic Proprietary Insulation Traps Warmth Even When Wet


The Marmot Nanowave 45 is an affordable summer sleeping bag that won’t take up too much room in your backpack. Not only is it cheap, it’s practical and functional which is why it’s our pick for the best backpacking sleeping bag under $100. 

In awarding it the winner of the best under $100 category, we realize it’s not quite fair because most other bags on this list have a temperature rating down to around 20 degrees. However, if you’re on a super tight budget and plan to camp from mid-spring to mid-fall, the Nanowave 45 is hard to beat.

Which leads us to the biggest downside of this bag, it is only good in mild weather. But, not everyone needs or wants a super warm bag and if you combine the Nanowave with an extra warm sleeping pad and a thermal liner, you might be able to extend the temperature range of this bag down a few degrees, making it much more versatile. If you’re looking for a warmer budget backpacking sleeping bag, check out the REI Trailbreak 20 which is also featured on this list. 

The Marmot Nanowave is also available in a 55-degree and 35-degree version.





Summer sleeping bags have a rating of 37°F and up. They are often light in weight because they provide less insulation and are highly packable. These are usually the more basic models, meant to protect you from the wind, but not ideal in very cold environments.

Three-season sleeping bags are best suited for traveling in spring and autumn but can also be used in summer, especially if you plan to pitch your tent in the high mountains where nights can be freezing. These models have more functionality than the summer ones: they often have hoods and other features to fight the coldest temperatures. The rating of these multipurpose bags is usually between 20°F and 32°F.

Sleeping bags with a rating below 20°F are meant to keep you warm in any environment, even in the snow. They have all the characteristics of the three-season sleeping bags, with an added layer of insulation to ensure greater protection. These bags are normally bulkier and heavier, but essential if you plan to sleep in environments where temperatures drop heavily during the night.



Sleeping bags made of synthetic materials do not absorb water and offer excellent protection from soil moisture or light rainfall. These types of sleeping bags are relatively cheap, but they can be bulkier and heavier than down sleeping bags.

Down insulation made from duck or goose feathers is the lighter in terms of weight. These bags can be compressed to a smaller size than synthetic, and they offer the highest protection against the cold. Down sleeping bags are generally more expensive than their synthetic counterparts and do not offer insulation when wet.



Any hiker knows how important it is to keep the pressure on their shoulders at a minimum, and therefore it is important to consider the weight of a sleeping bag before buying. Ultra-lightweight sleeping bags are best suited for backpacking, however, the reduced weight and bulk usually come at a high price. Summer sleeping bags are lighter than three-season and winter bags as they contain less insulating material, but consider the temperatures you’ll be sleeping at before looking at the weight you’ll be carrying.



When shopping for a sleeping bag, make sure you check how much space it will occupy in your backpack. Just because a sleeping bag is lightweight doesn’t necessarily mean it is also highly compressible. The volume of a compressed sleeping bag is measured in liters and you should aim at a maximum of 3 liters if your priority is reducing bulk.




Draft tube

The part of the sleeping bag running along with the zippers that is filled with insulating material to reduce the risk of cold air entering.



A water-repellent material.


Duck or goose down

The soft plumage that ducks and geese hide under their feathers, used as the insulating material in sleeping bags to protect against heat loss.


Synthetic insulation

Polyester fibers employed as the insulating material to prevent heat loss. A cheaper alternative to down.


Sleeping bag shell

A sleeping bag’s outer layer, usually made of water-repellent nylon.


Snag-free zippers

Zippers designed so that they don’t catch the sleeping bag’s fabric when pulled.