How to Choose Sleeping Bags for Backpacking
Kelty Cosmic Down 0 Sleeping Bag
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Remember trapezoids from 10th-grade geometry? This funky shape is ideal for helping sleeping bag baffles retain heat and is just one of the reasons the Kelty Cosmic Down 0 bag is a 3-season superstar.
Shop similar productsKey Details
Fill
550-fill-power down
Temperature Rating (F)
0 degrees (F)
- Lightweight and warm 550-fill-power down
- Innovative trapezoidal baffle construction improves thermal efficiency
- Buttery-soft and durable 20-denier nylon shell fabric with PFAS-free durable water repellent (DWR)
- Zippered internal stash pocket for headlamp or cellphone
- Zipper draft tube with anti-snag zipper design makes it easy to get in and out
- Dual slider for ventilation with locking zippers
- Natural-fit spacious footbox offers extra room to wiggle your toes
- Comes with stuff sack for quick departures
Imported.
Temperature ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth, since many different factors contribute to your comfort while you sleep. Backpacking bags are typically rated for temperature according to an independent testing protocol—currently International Organization for Standardization (ISO) 23537, though some older items followed European Norm (EN) 13537. Testing is based on a person wearing one base layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38.
Each bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
View the Kelty Cosmic Product LineView all Kelty Backpacking Sleeping BagsEach bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
| Best Use | Backpacking |
|---|---|
| Tested Lower Limit | 4 degrees (F) - ISO |
| Tested Comfort | 17 degrees (F) - ISO |
| Temperature Rating (F) | 0 degrees (F) |
| Temperature Rating (C) | -18 degrees (C) |
| Shell | 20-denier nylon taffeta |
| Zipper Location | Right |
| Insulation Type | Down |
| Fill | 550-fill-power down |
| Sleeping Capacity | 1-person |
| Lining | 50-denier polyester taffeta |
| Sleeping Bag Shape | Mummy |
| Stuff Sack Size | 10 x 19 inches |
| Stuff Sack Volume | Unavailable |
| Compressed Volume | Unavailable |
| Gender | Unisex |
Buying Advice
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Customer Images
Flaca76
Great on the trails
4 months ago
This sleeping bag is wonderful. I've used it on Mt. Whitney, Mt. Shasta, and Mt. Baldy, and it's perfect for me! I've had it for 3 years.
Age:45–54
Yes , I recommend this product
Greg
California
Great 0 degree bag at great price
1 year ago
Used this for the first time up at 12k altitude as an upgrade from my Kelty Cosmic 21 bag knowing it was going to be a cold trip. Well with frost on the tent, I was snug and warm inside. The zipper is large and easy to maneuver at night in the dark. The last night of the trip was warmer so opened up from the bottom of the bag for the body to get some cooler air in. Overall, if you're looking for a warm bag at a great price, I highly recommend.
Age:35–44
Yes , I recommend this product
DanaGH
Very warm and a great value.
2 months ago
I have had this sleeping bag for 4 years now, I absolutely love it. It’s very warm. I’ve taken into the Sawtooth mountains and the Whitecloud mountains and stayed warm every time. There are probably lighter bags, but I will sacrifice a little weight for sleeping warm. I only go backpacking once or twice a year, and find Kelly products to be the best bang for my buck. People who go more often may want to spend more for a lighter bag, but it has served me well.
Yes , I recommend this product
Eli
Warm, comfortable, ugly.
9 months ago
Real warm. Not the most handsome design in my opinion. Wife says it’s a bonus though- because no one will want to steal them.
Davhntr
California
1 week ago
I’ve had my Cosmic Zero degree sleep bag for over 10 years. I’ve taken it hunting in very cold temperatures. I had my tent collapse on me and wind and rain enter inside my tent. This sleeping bag did get wet, however it still kept me warm and dry. I highly recommend this bag. Davhntr
Dave B
NW New Mexico
HOT car camping bag
1 week ago
Nice, really warm bag for car camping. I've used it on a couple of Boy Scout campouts, and for early Fall, it's a bit too warm! but nice and roomy, with a big foot box. Looking forward to using it this Winter in the Colorado snow. Not light at all, but not planning to use for backpacking or snow shoeing. Note that it's not 100% down, but has synthetic fibers mixed in.
Age:65–74
Yes , I recommend this product
JTurner07
Virginia
Good for back sleepers
8 months ago
Nearly impossible to sleep on your stomach if you’re of larger size. Very warm over all though I just can’t sleep on my back. I am 6 feet 3 inches tall 250 pounds for reference
Age:18–24
No, I do not recommend this product
Bill47
For "Cold sleepers"
8 months ago
Haven't had a chance to try it, but it's gorgeous and feels like it will live up to the temp rating.