The Best Mummy Sleeping Bag for Comfort in the Cold

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If you’re in a rush and want to find out what the best mummy sleeping bag is, we recommend the Nemo Disco sleeping bag.

For all you car campers out there, how many of you use a rectangular sleeping bag when it’s time to go to bed at night? Probably many of you. They’re comfy, spacious, and can often be zipped together to allow couples to share one giant sleeping bag.

Perhaps you’ve been camping this way for awhile now, and you’ve decided to be a bit more adventurous. Maybe there’s a certain mountain that you’ve always wanted to spend a week exploring, or perhaps camping in the colder months is appealing to you. If that’s the case, you’ll want to find yourself a good mummy sleeping bag. We’ll cover everything you need to know, and offer a few of our own suggestions, so you’ll be prepared for your next adventure.

In this article, we’ll be reviewing the following mummy sleeping bags:

Temperature Rating

two tents pitched on the snow

I think it’s safe to assume that most of us like to be comfortable while we sleep. One of the biggest factors that influences this is the temperature, and your sleeping bag is going to be one of your primary sources of heat. The tent itself is great at blocking wind chill, and insulating against some of the colder, outside temperatures, but ultimately isn’t going to be effective at keeping you warm enough during the night.

Now, this isn’t going to be as important if you’re camping when it’s hot and muggy. In fact, you may even opt to lay down on top of your sleeping bag instead of inside it when the summer heat is weighing down on you! But once the climate starts to cool off, or if you find yourself camping in the mountains, you’ll want to pay more attention to the temperature rating for your sleeping bag.

Most bags come with two numbers:

  • Tested Comfort – the lowest temperature it can be where you’ll still feel relatively comfortable inside your sleeping bag. At this temperature, it won’t feel amazing, but you also won’t experience too much discomfort.
  • Tested Lower Limit – the lowest temperature it can be where you’ll stay safe inside your sleeping bag. You won’t be comfortable at this temperature, but you also won’t freeze to death.

A proper understanding of where you’ll be camping, and what the weather will be like, is necessary for determining what temperature rating you’ll want. Also keep in mind that the tested comfort rating only tells you the coldest temperature you’ll still be somewhat comfortable in. If it’s going to be 40 degrees Fahrenheit outside, you’ll want your tested comfort rating to be about 30 degrees. This will allow you to be truly comfortable during the night.

Sleeping Pad

When my dad first brought me camping, he wanted to avoid buying a sleeping pad for each of us. They tend to be thin, and somewhat expensive for the amount of cushion that they have, so he thought it was an unnecessary purchase. Thankfully, my mom convinced him to go for it. If she hadn’t, the camping trip would’ve been a lot more unpleasant!

Needless to say, we can’t talk about sleeping bags without mentioning their mandatory counterpart – sleeping pads. For backpacking purposes, I’m a fan of ones that are made out of closed cell foam. They don’t offer as much padding or insulation as some of their relatives, but I love how lightweight and easy to pack away they are. You can also choose some that are inflatable or have thicker foam padding if that’s something you would prefer. Try to find something with a high R-value, as this will provide better insulation between you and the ground.

Backpacking vs Car Camping

people trekking through the wild with backpacks

The great thing about mummy bags is that they can be used no matter what you’re doing. There’s no harm in making it your bed while car camping, and they’re the ideal piece of gear for backpacking trips. Rectangular sleeping bags on the other hand? Well, they’re really only useful if you don’t plan on walking long distances with them.

A good backpacking sleeping bag is going to be different from a car camping sleeping bag in a few ways:

  • They’re lightweight and easy to pack down
  • They have better warmth and insulation, despite there being less material

Obviously, there are a few cons as well. They fit snugly, tend to be less comfortable, and don’t give you any room to stretch out or turn over in your sleep. But for the job that they’re meant to do, mummy bags are worth the tighter squeeze for how easy they are to pack away and how well they keep you warm at night.

Unlike rectangular sleeping bags, mummy bags have a hood that covers over your head to help prevent heat from escaping. So even if you don’t plan on backpacking, mummy bags are essential for cold weather car camping, to ensure that you stay as warm as possible for as long as possible.

Best Mummy Sleeping Bag Reviews

REI Co-op Trailbreak Mummy Bag

REI is known for being a popular outfitter for campers, selling brands like Nemo, Marmot, and many other high end products. But sometimes these items overshadow REI’s own exclusive brand, which I have found to be of equal quality (if not better) than many of the other mainstream products out there.

The Trailbreak mummy bag is one of these items. It’s a nicely shaped bag that hugs the contours of your body for better heat retention, while still providing enough wiggle room so you don’t feel claustrophobic. I’m a big fan of a large footbox too, since I hate the feeling of my legs and feet being restricted.

The 3 panel hood is great at keeping cold air out, and it even comes with differentiated drawcords (one round, one flat) to help you adjust the head and neck area even when you can’t see what you’re doing. There’s also a full draft tube and face muffler for added warmth. The fill is synthetic, so even if it gets wet, it will continue to do its job properly, unlike sleeping bags with a down fill. But who said anything about getting wet? There’s a durable water repellent on the outside of the polyester sleeping bag material, allowing you to stay dry even if it’s wet on the outside.


– Differentiated drawcords
– Waterproof shell
– Tested lower limit of 29 degrees
– Water resistant fill
– Large footbox


– Zippers snag easily
– A bit tight in the shoulders

Nemo Forte – Women’s Sleeping Bag

When it comes to Nemo, I’m a fan of most of their products. Though they tend to be more on the spendy side of the spectrum, it makes sense given the overall quality of the gear. While the Forte is about twice as expensive as the Trailbreak listed before it, the sleeping bag itself is more developed and home to a variety of fancy features.

For example, there’s more room around the elbows and knees, allowing side sleepers the opportunity to rest in their favorite position. Considering 70% of the population sleeps on their side, and most mummy bags aren’t big enough to accommodate this, I’d say it’s a pretty useful feature.

Also, if you look at the picture on the right, you may notice the two, light blue vertical slits in the bag. Those are called Thermo Gills, and they allow you to let some of your body heat out of the sleeping bag without letting any drafts come in. That way, you’ll be able to enjoy milder night inside your bag without getting too hot in the process. And trust me, you won’t have any trouble staying warm in here. Nemo realized that women tend to run a little colder than men, so they made sure to pack in the insulation, providing temperature ratings that will easily see you through Spring, Summer, and Fall.


– Highly insulated and cozy
– Thermo Gills allow customized heat retention
– Extra room in the elbows and knees for side sleepers
– Waterproof material to withstand tent condensation
– Integrated pillow pocket


– Because it’s so big, it’s hard to stuff back into the compression sack
– Getting the right size can be hard – if you’re on the fen

Nemo Disco Sleeping Bag

Though not a “true” mummy bag, Nemo’s Disco sleeping bag still offers high quality warmth and insulation within its semirectangular shape. It’s going to be a bit more bulky than many of its counterparts, but there’s a good reason for that. All of the extra insulation puts the tested lower limit on this bag down to 14 degrees, which is low enough for most types of winter camping.

The down fill is incredibly warm and hydrophobic, meaning it won’t soak up water as easily. Considering down loses its insulation ability when wet, this feature is quite useful if you expect to get your bag drenched in water. Even so, it won’t be easy for any kind of liquid to penetrate the nylon shell.

Additionally, the Disco shares quite a few features with the Forte listed above. There’s additional room in the elbow and knee region, making it easier for side sleepers to twist and turn during the night. And the Thermo Gills allow body heat to escape without letting drafts in, so you’ll be able to regulate the internal temperature to your liking. And trust me…you’ll get warm in this sleeping bag. I wouldn’t recommend sleeping inside it during the summer months, but there’s so much insulation that it makes a great bed if you lie on top of it.


– Thermo Gills
– Lots of extra room to move around
– Draft tube
– Hydrophobic down fill
– Rated for very cold temperatures


– The drawstrings near the head can be uncomfortable
– Because there’s a lot of extra space inside, it can take longer for it to warm up

Sea to Summit Spark Sleeping Bag

For backpackers especially, the weight of each individual piece of gear is a major consideration. A few extra ounces makes a big difference when you’re trekking with all your belongings on your back, which is why an ultralight sleeping bag is an invaluable resource. The Spark, by Sea to Summit, fits the bill in this regard, weighing in at a mere 12 ounces for the regular size. That’s pretty good, especially since the regular sized Nemo Disco mentioned above weighs 2 pounds 11 ounces!

Of course, it really boils down to what you’re looking for in a sleeping bag. The Spark might be lightweight, but it’s not going to be your best option in colder temperatures. Below freezing, especially, you’ll start to feel pretty uncomfortable. I’d suggest this product for those of you who enjoy long treks during late spring to early fall, and don’t necessarily want to do any mountain camping before May or after September. For how light it is, the fill is shockingly warm, but not enough to be used in more extreme conditions.


– Ultralight
– Decent heat retention considering how light it is
– Vertical chest baffles to prevent the insulation from migrating
– Nice mummy contouring for maximum efficiency


– It’s quite tight and the zipper is short, so getting in and out can be a challenge
– A bit on the expensive side

Marmot Never Summer Sleeping Bag

Never Summer is an interesting name for a sleeping bag, isn’t it? Perhaps you might have guessed it, but this bag actually lives up to its name in the sense that you won’t want to use it in the summer! Rated for temperatures down to 0 degrees (yes, you read that right), Marmot put a lot of effort into this cold weather product. And in the process, they made it practically unusable in temperatures above 60 degrees, simply because of how hot it gets inside.

But generally speaking, you’re probably not getting a mummy bag because you plan on using it in hot weather. And if you want one for backpacking, grab the Spark by Sea to Summit listed above – this “Never Summer” bag is too heavy for backpacking purposes, unless you’re going in the colder months. At just over 3 pounds, you’ll definitely feel it in your pack.

The duck down is what’s taking up a lot of that weight, though, and is something you’ll be happy to have when temperatures drop below freezing. And if the wraparound footbox and multi-baffle hood aren’t enough to keep you warm, there are a couple of pockets inside the bag where you can stuff hand warmers.


– Really warm
– Internal stash pocket
– Nylon shell with water repellent finish
– Extra short zipper on the right side that makes it easy to access the hood


– Weight
– Snagging zippers


Mummy bags are the ideal sleeping space for extreme campers. They’re well insulated, lightweight, and tend to pack down well, so you can tackle long hikes and cold temperatures with ease. From an overall versatility standpoint, our favorite mummy bag is the Nemo Disco because of its temperature rating, comfort level, and other handy features.

Though not designed for winter camping, you can certainly get away with using it late into year. It’s puffy and warm, but not unbearably snug like many mummy bags can be, since it has extra room in the elbows and knees. And if it gets too hot on those milder nights, just open up those Thermo Gills to let some heat escape without worrying about a draft coming in.

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Spencer Yeomans

Spencer Yeomans

A lover of the outdoors, and especially the mountains, Spencer has always enjoyed pushing people to step outside their comfort zones. His mission is to help others get out of their homes to have fun and stay active in nature.

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