Kelty Cosmic Down 20 Sleeping Bag Review
our favorite Affordable and durable camping and backpacking sleeping bag with genuine down insulation
October 9th, 2025
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Our verdict
The Kelty Cosmic 20 down sleeping bag is our choice for best bang-for-your-buck camping sleeping bag. It is an excellent choice for your first sleeping bag. The Kelty Cosmic Down 20 has many features and design elements found in sleeping bags three times the price. Plus, it is compact and light enough to use for backpacking trips, too. If you know you want to invest in a sleeping bag and want to spend less than $175, we don't think you can beat the Kelty Cosmic Down 20.
"Budget down sleeping bag" is almost an oxymoron. Down is by nature more expensive than many synthetic-filled sleeping bags—especially if it is DriDown, or treated to be water-resistant. But a down sleeping can continue to feel warm for 10 years or more, unlike a synthetic bag that gradually loses its ability to insulate. We personally find down to feel softer, loftier, and more pillow-like than synthetic bags. Plus, it is more compact and takes up less space in your backpacking backpack. That's true for high-end sleeping bags and it's true for the Kelty Cosmic Down 20, too.
Unless you're vegan, if you camp at least once a year and plan to keep doing that for the next decade or so, we think you'd be better served going with a down bag.
The Kelty Cosmic Down is a mummy bag, but surprisingly roomy. While not our first choice for backpacking, its 2.5-pound weight and 10.7L stuff sack size is decent for backpacking, especially considering the price. The Kelty Cosmic Down 20 is our go-to sleeping bag for car campers, cabin and summer camp trips, sleepovers, and entry-level backpackers.
Kelty Cosmic Down 20 Sleeping Bag
men's
Women's
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Kelty Cosmic 20 Sleeping Bag specifications
Temperature Rating: 20°F (-7°C) / ISO Comfort 31°F / ISO Limit 21°F
Weight: Short: 2 lbs 3 oz / Regular: 2 lbs 7 oz / Long: 2 lbs 11 oz
Fill: 550-fill-power down
Fill Weight: Short: 14.6 oz / Regular: 16.4 oz / Long: 18.8 oz
Shell: Recycled 50D polyester taffeta
Lining: Recycled 20D nylon taffeta
Shape: Mummy
Best for: Budget backpacking, car camping, 3-season use
Stuff Sack Size: Regular: 8" x 13" (10.7L)
Price: $170-200 (depending on length)
Comparison table
Hello, World!
Who is it for?
Budget-conscious backpackers seeking down insulation without premium pricing
Beginning backpackers wanting a reliable entry-level down sleeping bag with many of the features of a higher-end bag
Car campers who occasionally backpack and need versatile performance
Casual hikers prioritizing value over ultralight weight savings
Families outfitting multiple people on a budget for outdoor adventures
How we tested
Kelty Cosmic 20 sleeping bag being tested on a backpacking trip in the Eastern Sierra.
We have been testing the last few models of the Kelty Cosmic 20 sleeping bag for the past three years in everything from sub-freezing temperatures to balmy summer days. In all, we've spent about 50 nights camping in this bag for this review.
Treeline Review writer Micah Leinbach tested an earlier version for his Best Camping Sleeping Bags guide, testing while working at a summer camp in humid and warm Midwest temperatures and in North Carolina. He even tested inside a walk-in refrigerator to simulate the cold!
Treeline Review editor Liz Thomas has since gone on to test the newest version for a month straight of camping and backpacking in the Eastern Sierra. Liz tested the Kelty Cosmic 20 sleeping bag using camping cots, camping mattresses, and on backpacking sleeping bags.
Treeline testers have slept in the Kelty Cosmic 20 in camping tents, backpacking tents, and in doors in cabins and canvas-sided tent cabins. We've used it for sleepovers on the ground in the living room and on couches at friends' houses.
We tested the Kelty Cosmic on warm rainy days, on cold rainy days, on misty days, and on sunny days.
In all, we've five campers sleep in this bag. We've had back-sleeping testers and side-sleeping testers and belly-sleeping testers. We had testers of different body shapes and sizes, ages and metabolism rates, from self-described "hot sleepers" to "cold sleepers."
Most importantly, we tested the Kelty Cosmic 20 sleeping bag side-by-side against similarly priced bags from REI Co-op, EXPED, and even a budget sleeping bag we got for free from a car insurance company.
We tested the Kelty Cosmic 20 based on different needs, taking into account the trade-offs between price, weight, packability, long-term durability, features, and comfort. Warmth wasn't really negotiable.
What we liked
A down sleeping bag lasts many years longer than synthetic (i.e., will continue to be warm and keep its insulating properties)
Versatility for camping and backpacking
Value for the price
What could be better
The "20" in the name Kelty Cosmic 20 refers to the men's rating/extreme rating. This is really more of a ~30°F-40°F bag and colder sleepers should judge it by Kelty’s Comfort Rating number, not the name on the bag.
The feel of the recycled taffeta fabric against the skin wasn't the softest
Features
Trapezoidal baffle construction improves thermal efficiency over standard baffles
Down insulation and warmth
The Kelty Cosmic down uses a DriDown 550-fill-power down, which hits the sweet spot in terms of a good warmth-to-weight ratio for the price while letting you have many of the water-resistant benefits of a synthetic sleeping bag.
On top of that, Kelty uses some clever designs and sewing techniques to give you the most out of the insulation. The trapezoidal baffle construction gives you a boost in thermal efficiency over traditional baffles you'd see in other budget sleeping bags. It costs a little more to do that kind of sewing, but it is still a great bang for the buck compared to adding more down or higher fill power down.
Water resistance and DriDown Treatment
For that first level of protection, the bag has a PFAS-free Durable Water Resistance (DWR) treatment, which provides water resistance that will cause droplets to bead up on the shell fabric and then roll off. This prevents water from soaking through and reaching your down in the first place. You can learn more about why PFAS-free is important in DWR in our guide on forever chemicals.
Kelty also uses DriDown treatment to help the insulation retain loft when exposed to moisture. This is awesome for campers and beginner backpackers, or anyone who lives somewhere wet. Many campers and backpackers are very concerned about their sleeping bag getting wet. Traditional down loses its insulative capabilities when wet, becoming a soggy wet mess. Synthetic insulation can often retain 75 percent or more of its loftiness and insulative properties even when wet. DriDown is more like synthetic insulation. To be clear: I wouldn't purposely try to throw it overboard on a canoe trip, but if your water bottle spills or tent leaks, you should be OK.
Draft collar and draft tube
The Kelty Cosmic Down 20 has features that we generally see in higher end bags and the one that impressed us the most for a sub-$175 bag was the draft collar and draft tube along zipper to prevent heat loss.
Mummy shape
Traditional mummy shape balances thermal efficiency with comfort
Most backpackers and many campers like a mummy shape on their sleeping bag because it maximizes thermal efficiency. The mummy shape also gives you some weight savings, which is appreciated while backpacking. It slightly helps with packability as well, which is useful whether you're trying to fit this bag in a backpacking backpack or trying to fit it in your vehicle for a camping trip.
Mummy shapes aren't for everyone, though. If you prefer a rectangular shaped bag, consider the REI Siesta Hooded sleeping bag. If you want a mummy bag that feels less like a traditional mummy bag (and are willing to pay for a high-end bag), the NEMO Disco 15 Endless Promise is another top choice.
The hood design on the Kelty Cosmic 20 can fit small backpacking pillows and we found it provides good head coverage on colder nights.
Durability and construction
The Kelty Cosmic Down has a robust build quality that can handle rougher treatment better than many of the lightweight and ultralight camping and backpacking sleeping bags we've tested over the years. Like all sleeping bags, I wouldn't completely toss this one around, but this would be the bag I'd recommend for people who know they are rough on their stuff.
The Kelty Cosmic 20 uses a recycled 50D polyester shell fabric that offers excellent durability for frequent use. It wasn't the softest, but we also trusted its durability. We dragged it around through sagebrush while transferring this bag from tester to tester, ten to tent, and never had issues. I wouldn't have trusted a lot of sleeping bag shell fabrics with that.
The 20D nylon inner lining provides a softer feel. It's still not the softest, but this is also designed to resist wear and tear. We've had testers tear out the lining on other sleeping bags and it's definitely something that can happen and can ruin your night, especially when down feathers go flying. With the lining on the Kelty Cosmic, I was never worried it would develop a hole from a long toenail or a pine needle or stick that accidentally came in on your pants.
The Cosmic 20 uses a reinforced zipper that reduces snagging on fabric. Snagging your zipper on the surrounding shell fabric is up there with the top five most annoying things that can happen in camp. If you do run into issues, check out our How to Fix Zippers on Outdoor Gear guide.
Practical features
Internal stash pocket keeps headlamp, phone, and essentials within reach.
The Kelty Cosmic Down 20 has some higher-end features, including an internal zippered stash pocket to keep lip balm or your headlamp close at hand.
It also has a foot-shaped footbox that provides extra room for feet and sleeping positions. This helps prevent your feet from feeling as cold at night by reducing the chance your toes will compress the down insulation around your toes.
It has a full-length zipper with anti-snag design for temperature regulation. And it's maybe a little gimmicky, but we liked the glow-in-the-dark zipper pull. It's supposedly there to make it easier to find your zipper if you have to get up to pee at night, but mostly it's just fun to look at.
A less gimmicky feature we liked is that the bright interior lining makes finding lost items easier. As someone who often camps with a small stuffed animal that often gets lost, I appreciated this feature. I also store my phone by my footbox in sub-freezing temperatures to protect the battery and the bright interior makes it easier to find that, too.
Fit and sizing options
The Kelty Cosmic is available in Short (fits to 66"), Regular (72"), and Long (78") lengths. We recommend getting the bag that is as close to your height as you can (but round up). That means it'll be easier and faster for you to warm up the air inside the bag. Perhaps counter-intuitively, sizing down won't help you stay warmer because the down will not be as insulative if your feet are pressing against the sides (and footbox) of the bag.
We also like that Kelty makes a women's version with additional down for more warmth. Unfortunately, it's harder to find and not available at all retailers. We also found the pricing to be more expensive.
Sustainability features
Kelty uses some sustainability features, Many budget bags skip sustainability features in favor of a lower price. The Kelty Cosmic Down 20 made from recycled polyester shell and nylon lining materials and so is the stuff sack. It uses a PFAS-free water repellent treatment. The down is responsibly sourced with tracking to ensure ethical practices.
Most of all, it uses durable construction and reduces need for frequent replacement. We at Treeline Review believe that the most sustainable choices are buying right the first time to reduce what ends up in a landfill and the amount of gear that is manufactured and shipped around in the first place. Choosing gear you love and will hold onto and use for a long time is the most sustainable option and we think the Kelty Cosmic sleeping bag fits that bill.
Performance in the field
Warmth
Despite its somewhat misleading name, the Kelty Cosmic Down 20 sleeping bag is comfortable to its stated 31°F comfort rating. It is usable to 20°F if you are wearing layers and socks and have a well-insulated camping mattress or sleeping pad underneath and are sleeping inside a camping tent. We had no issues with the warmth while camping during summer at 8,000 feet or in the Midwest in late spring to early fall. We had no issues sleeping in unheated cabins with this bag, either.
One thing we've learned about warmth is it really pays to have a dedicated pair of sleeping clothes. And before you sleep, wipe off salt and sweat from the day. See more tips in our How to Stay Warm at Night while Camping and Backpacking guide.
Packability
For a budget bag, we were pleased with how well the Kelty Cosmic Down 20 sleeping bag compresses. It comes with a 10.7L stuff sack that comes out to about 8" x 13". That size fits into a backpacking backpack with no issue and is easily squishable into a jam-packed car trunk for car camping. Like all sleeping bags, for long term storage, you need to store it uncompressed in a much bigger stuff sack.
Durability
Compared to the budget bags we tested, the Kelty Cosmic 20 really excels at durability. The thick fabrics could handle being dragged around in sagebrush and thick aspen and Ponderosa pine forests from tester to tester with no issue.
Comfort
Kelty Cosmic 20 sleeping bag being tested in colder conditions
We found the traditional mummy fit works well for back and side sleepers. We found the Kelty Cosmic has adequate shoulder and hip room for most body types. If you want more room or are looking for a plus-size or big and tall friendly bag, see our guide to Best Plus-Size Outdoor Gear.
Moisture resistance
We found the DriDown treatment and DWR on this bag help with moisture resistance. But the best line of defense to protect your sleeping bag from getting wet is a good stuff sack and making sure you use a liner in your backpacking backpack. Like all sleeping bags, it requires care in wet conditions.
Kelty Cosmic 20 vs. similar sleeping bags
The Kelty Cosmic 20 is a more affordable sleeping bag than many similar on the market, especially for a down bag. Its materials tend to be more durable, which makes this a good choice if you know you are hard on your gear. It doesn't have quite the sustainability features you'd find in the Marmot Trestles Elite Eco 20 or the EXPED DeepSleep, though it does use recycled material.
If you are willing to spend more, you can get similar features in a lighter weight and more packable down bag with the NEMO Disco sleeping bags or REI Magma bag. The shell and liner fabric is softer on those bags, but it is also less durable.
If you're buying your first sleeping bag, we think the Kelty Cosmic 20 is a good choice. It has a lot of the features you'd find in a higher-end bag but is sub-$175. This bag could be all your need for camping and some backpacking for a long time. And if you find that you get more into camping and backpacking, you'll already have been introduced to some higher-end features by starting with the Kelty Cosmic 20.
Should I buy the Kelty Cosmic 20?
Buy if: You want genuine down insulation on a budget and prioritize durability over ultralight weight
Skip if: You need maximum warmth for cold conditions, ultralight weight for long-distance hiking, or prefer roomier semi-rectangular shapes. Also skip if you are vegan or allergic to down feathers.
men's
Women's
Where to buy the Kelty Cosmic 20?
The Kelty Cosmic 20 sleeping bag is a popular gear its, so you have options when it comes to retailers. However, not every retailer sells the women's version, so keep that in mind if you want a version that will sleep warmer. We tested the men's / unisex version.
Here are some of the pros of the retailers that sell the Kelty Cosmic Down 20 sleeping bag.
REI
Pros: 100% satisfaction policy for 1 year; 10% dividend for members.
Backcountry
Pros: Frequent sales for Expedition Perks members (free to join), fast shipping, Gearhead chat customer service is excellent
Campsaver
Pros: Free shipping and free returns on sales over $50.
Kelty
You can sometimes find more options when purchasing directly from the retailer. Sometimes, purchasing directly from the retailer can make it easier if you need to make a warranty return, such as if there is a defect.
Similar products
REI Trailmade 20
Temperature rating: 21°F (-7°C) / ISO Comfort 31°F / ISO Limit 21°F
Insulation: Synthetic
Style and shape: Mummy
Packed size: 9L
Weight: 3.3 lbs
The REI Trailmade 20 is a winner in our Best Camping Sleeping bags guide for its excellent value for the price. This mummy bag comes in many lengths and has a full hood for a snug and warm night of sleep. However, as a synthetic bag, it likely won't last you as long as a down sleeping bag. You can sometimes find the REI Trailmade sleeping bag on sale for under $100, so if you know you want a synthetic bag, this is a good choice.
REI Trailmade 20
Temperature rating: 20°F (-7°C) / ISO Comfort 32°F / ISO Limit 20°F
Insulation: Synthetic
Style and shape: Mummy
Packed size: 9.8 x 11
Weight: 4.0 lbs
The EXPED DeepSleep is a budget camping sleeping bag and backpacking sleeping bag that also provides a lot of value. It is a mummy bag, but isn't available in as many lengths and sizes. It costs less than the Kelty Cosmic 20 but has many features you'd find in higher-end sleeping bags, including a draft tube and a pocket for lip balm or your headlamp.
The DeepSleep is 100% recyclable, meaning that when the life of the bag is over, the synthetic insulation and the shell can all be recycled. However, it is not made of down and in our experience, synthetic sleeping bags don't last as long or stay as warm over extended periods of time. Nevertheless, if you're going for a synthetic bag, we think this is an excellent choice.
EXPED DeepSleep
Marmot Trestles Elite Eco
Temperature rating: 20°F (-7°C) / ISO Comfort 24°F / ISO Limit 12°F (men’s) and 30°F (-7°C) / ISO Comfort 29.7°F / ISO Limit 18.7°F (women’s)
Insulation: Synthetic
Style and shape: Mummy
Packed size: 18.9 x 9.4 (men’s) and 18.9 x 10.6 (women’s)
Weight: 3.5 lbs (men’s), 2.7 lbs (women’s)
Like the EXPED DeepSleep, the Marmot Trestles Eco is 100% recyclable, meaning that when the life of the bag is over, the synthetic insulation and the shell can all be recycled. However, like the EXPED, as a synthetic sleeping bag, it will likely not last as long or stay as warm over extended periods of time.
Marmot Trestles Elite Eco
men's
Women's
Why you should trust us / About the author
Liz Thomas using the Kelty Down Sleeping bag for camping out under the stars on a camping cot.
To test the Kelty Cosmic 20, Liz Thomas slept in this sleeping bag for a month in the Eastern Sierra in everything from sub-freezing temperatures to hot summer days and nights and in extreme wind. In addition to Liz testing, 4 other people also camped in this sleeping bag, ranging from 5'2' to 6' and hot and warm sleepers, adding their perspective on the warmth, fit, and comfort.
Liz is an award-winning Los Angeles-based writer and Editor-in-Chief of Treeline Review. A former Fastest Known Time (FKT) record holder on the Appalachian Trail, Liz came to Treeline Review from New York Times/Wirecutter, the New York Times’ product review site, where she was a staff writer on the outdoor team.
Liz has talked about outdoor gear on Good Morning America (TV), in The Wall Street Journal, The Guardian, Men’s Journal, Women’s Health, and Outside Magazine.
You can read more about Liz at her wikipedia pagehere or onher website. See all her Treeline Review articles on herauthor page.
