Updated on February 19, 2021

Chilly weather shouldn’t keep you from getting outside, but when you’re camping in the cold, you need a sleeping bag that will keep you from freezing. A 0 degree sleeping bag is a great choice for camping in a variety of seasons, but how do you choose the right one to warm you up? Here at The Adventure Junkies, we’ve sorted through a variety of options to help you choose the best 0 degree sleeping bag to keep you cozy on your cold adventures.

For more of our top backpacking gear recommendations, check out the Best Backpacking Sleeping Bags.


Quick Answer - The Best 0 Degree Sleeping Bags

  1. Marmot Never Summer 0
  2. Sea to Summit Ascent AcIII
  3. Marmot Ouray
  4. Big Agnes Orno 0
  5. REI Co-op Down Time


Comparison Table - Best 0 Degree Sleeping Bag

PictureNameShapeWeightZipper LocationPriceRating
Marmot Never Summer 0Mummy3 lbs. 3oz.Left$4.8
Sea to Summit Ascent AcIIISemi-rectangular2 lbs. 14oz.Left$$4.7
Marmot OurayMummy3 lbs. 10oz.Right$4.9
Big Agnes Orno 0Mummy2 lbs. 7oz.Left$$$5.0
REI Co-op Down TimeMummy3 lbs. 14oz.Left$4.5
PictureNameShapeWeightZipper LocationPriceRating
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 Backpacking 0 Degree Sleeping Bag

Marmot Never Summer 0

  • Weight: 3 lbs. 3oz.
  • Shape: Mummy
  • Zipper Location: Left
  • Two Zipper System Keeps Cold Air From Getting In Or Provides Extra Ventilation
  • Pocket In Footbox For Holding A Handwarmer To Keep Your Toes Warm
  • Collar Is Down-filled To Keep You Extra Cozy


The Marmot Never Summer 0 Sleeping Bag has a water repellent nylon shell surrounding water repellent 650-fill-power down insulation to keep you warm when the temperature drops, even if moisture accumulates in your tent. The Never Summer is a mummy shaped bag to keep the heat close to your body, yet it has a roomier anatomical footbox that doesn’t constrict your feet while still keeping your toes toasty. In fact, a pocket in the footbox is designed specifically to hold a hand or foot warmer packet if you need an extra boost of warmth. The zipper is backed with a full length draft tube to keep warm air in and cold air out, while a second zipper allows for ventilation when necessary.

Sea to Summit Ascent AcIII

  • Weight: 2 lbs. 14oz.
  • Shape: Semi-rectangular
  • Zipper Location: Left
  • Semi-rectangular Shape Gives You More Hip Room Than Mummy Shape
  • Additional Half Zip On One Side Offers Extra Ventilation
  • Can Unzip Completely To Use As A Quilt


With zippers galore for a variety of configurations, the Sea to Summit Ascent ACIII is a 0 degree sleeping bag that you can zip together with another bag or unzip completely to lay flat as a warm winter quilt. You can also unzip one side like a standard sleeping bag, half unzip the top layer if you need extra ventilation, or unzip just the footbox if your feet start to sweat.

The Sea to Summit Ascent ACIII is designed with vertical baffles on the torso, which keep the insulation in place inside the bag and prevents cold spots. The semi-rectangular shape also provides a bit more room than a mummy-style bag, so you can sleep comfortably.

Marmot Ouray

  • Weight: 3 lbs. 10oz.
  • Shape: Mummy
  • Zipper Location: Right
  • Anatomically Designed To Better Fit A Woman’s Body
  • Additional Insulation In Areas Prone To Heat Loss
  • Wraparound Footbox Keeps Toes Extra Warm


Women often run colder than men and bags that are too roomy to fit properly only exacerbate that problem. The Marmot Ouray 0 Degree Sleeping Bag is designed to better fit the anatomy of a woman’s body, with extra room at the hip area and narrower shoulders. Plus, the Ouray has extra insulation in areas that are more prone to losing heat.

Combining the insulated hood with a down-filled collar helps keep your head cozy, while a wraparound footbox keeps your feet extremely warm while still giving them room to move. If you happen to get too hot, a second zipper allows you to fold down the top layer of the bag for additional ventilation.

Big Agnes Orno 0

  • Weight: 2 lbs. 7oz.
  • Shape: Mummy
  • Zipper Location: Left
  • Footbox Is Ergonomically Designed For Extra Warmth
  • Loops On The Outside Allow For Hanging Drying & Storage
  • Hood Drawcord Is Easily Adjustable


When you need to stay warm without adding extra weight, the Big Agnes Orno UL is an excellent sleeping bag solution. Although it is packed with 850-fill-power water repellent down, the streamlined mummy shape and minimal zipper keep the Orno UL from tipping the scales. The included stuff sack lets you easily compress the bag down to fit in a small space in your pack.

A draft collar around your head will keep the cold out while the low-profile drawstring cord on the hood is easily adjustable with one hand and stays out of the way when you’re sleeping. If you need extra insulation, loops on the interior of the bag allow you to easily attach a sleeping bag liner inside the bag so it won’t slip down to your feet at night.

REI Co-op Down Time

  • Weight: 3 lbs. 14oz.
  • Shape: Mummy
  • Zipper Location: Left
  • Relaxed Fit In The Torso Lets You Move While Keeping You Warm
  • Hood With Face Muffler Helps Your Head Retain Heat
  • Loops To Attach Sleeping Pad


Zero degree sleeping bags can be quite expensive, but the REI Co-Op Down Time is an affordable option that will protect you from the cold. This is a mummy bag, but it is designed with a slightly relaxed fit to balance keeping you warm while offering comfort to not constrict you while you’re sleeping. The bag also is structured to fully enclose your shoulders and has an oversized face muffler to really insulate your upper body and head.

One tradeoff to the low price point of this bag is that it is somewhat heavier than other 0 degree bags, so if weight is a concern for you, it might be worth investing in a lighter sleeping bag.




Although temperature ratings of sleeping bags are standardized, it can still be confusing to understand in what conditions a 0 degree sleeping bag will keep you warm. Your entire sleeping setup (clothing, sleeping pad, tent) can affect how warm and comfortable you’ll actually feel at night, and, of course, each person’s body regulates temperature a little differently. REI put together a guide explaining how sleeping bag temperature ratings work.


Down fill power differs between 0 degree sleeping bags and makes a difference in both weight and warmth. But what exactly does it mean? Basically, it describes the quality of the down. A higher number provides better insulation (but is not necessarily warmer) and is usually much more expensive. This article from REI goes into more detail about down fill power.



Many 0 degree sleeping bags are mummy-shaped, which means they fit tight to the body. This offers extra warmth while also cutting weight since it eliminates extra fabric and insulation. However, mummy bags can feel quite restrictive since you don’t have much room to move.

Semi-rectangular bags give you a little more space so you’re more comfortable when you sleep. These bags might weigh slightly more, but if they are well-designed, they should still be able to keep you warm.



Most sleeping bags have full-length zippers on just one side, so if you have a preference due to your dominant hand or the side of your tent the door is on, try to choose a bag that won’t frustrate you with a zipper on the wrong side.

Many 0 degree sleeping bags also have a second partial zipper to give you extra ventilation. Some even have zippers at the feet or can unzip fully to lay flat if you need a blanket.





Fabric separators that keep down insulation in place.


A tube filled with insulation that backs the length of the zipper to block cold from entering.


An insulation-filled collar to provide extra warmth at the neck.


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