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Kelty Cosmic 0 Review

An inexpensive option that will keep you warm, but too heavy for moving light and fast in the mountains
Kelty Cosmic 0
Photo: Backcountry
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Price:  $250 List | $181.96 at Backcountry
Compare prices at 3 resellers
Pros:  Warm, inexpensive
Cons:  Heavy, large packed size, not very weather resistant
Manufacturer:   Kelty
By Matt Bento ⋅ Senior Review Editor  ⋅  Dec 24, 2020
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39
OVERALL
SCORE


RANKED
#13 of 13
  • Warmth - 20% 5
  • Weight - 20% 2
  • Comfort - 20% 5
  • Packed Size - 15% 3
  • Weather Resistance - 15% 3
  • Features - 10% 6

Our Verdict

The Kelty Cosmic Down 0 is one of the heaviest, least weather-resistant bags in our review, but it is also the least expensive, and the competition among the bags we selected to review is fierce. You get a bag that still fulfills the primary job of a cold weather sleeping bag—keep you warm. Despite the low price, the Cosmic Down still has great features like a draft collar and full-length draft tube to shield you from winter winds. While not the most comfortable bag we tested, there is still ample room for side sleepers. If you're looking to do some cold weather car camping or short overnights without going for broke, this contender is a good option.

Looking for a three-season bargain?
The Kelty Cosmic 20 is another bargain for a three-season backpacking sleeping bag. For the impressively low price tag, Kelty gets the job done with a reasonably warm, decently comfortable, and semi-lightweight sleeping bag. If you're looking for an affordable all-arounder but don't need the warmth of the Cosmic 0, the Cosmic 20 might be the perfect match.

Compare to Similar Products

 
Kelty Cosmic 0
This Product
Kelty Cosmic 0
Awards  Editors' Choice Award Top Pick Award  Best Buy Award 
Price $181.96 at Backcountry
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$710.00 at Backcountry
Compare at 2 sellers
Check Price at REI
Compare at 2 sellers
$209.99 at Backcountry$259 List
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Pros Warm, inexpensiveWarm, awesome comfort, great warmth to weight ratioComfortable, spacious, lightweight, elasticized baffles allow you to sit cross leggedPlenty warm, comfortable hood, bomber outer fabricAffordable, water-reppelent, roomy, warm
Cons Heavy, large packed size, not very weather resistantExpensiveSignificantly less warm than similarly rated bag, enormous footbox, ventsLow end down, substantially heavier than many other bagsHeavy
Bottom Line An inexpensive option that will keep you warm, but too heavy for moving light and fast in the mountainsFor temps down to zero degrees, you can't beat this bagThis comfort-focused bag has a wide, roomy cut and vents for temperature controlThis is a great option for a budget bag with occasional winter overnights in mindThis is an excellent bargain for a capable winter camping sleeping bag
Rating Categories Kelty Cosmic 0 Kodiak MF NEMO Sonic 0 Mountain Hardwear R... REI Co-op Down Time 0
Warmth (20%)
5.0
8.0
6.0
7.0
6.0
Weight (20%)
2.0
7.0
6.0
5.0
2.0
Comfort (20%)
5.0
8.0
9.0
7.0
6.0
Packed Size (15%)
3.0
7.0
6.0
7.0
4.0
Weather Resistance (15%)
3.0
7.0
7.0
6.0
5.0
Features (10%)
6.0
7.0
9.0
7.0
6.0
Specs Kelty Cosmic 0 Kodiak MF NEMO Sonic 0 Mountain Hardwear R... REI Co-op Down Time 0
Measured Weight (lbs, size Regular) 3.80 lbs 2.85 lbs 2.95 lbs 3.20 lbs 3.87 lbs
Fill Weight (oz) 33 oz 30 oz 24 oz 33.2 oz 27 oz
Type of Down Fill DriDown Goose Down Down RDS Certified Down RDS Cert/Fluorine Free Duck Down (RDS certified and bluesign approved)
Fill Power 600 850 800 650 650
Material Weight (excludes down, oz) 28 oz 15.65 oz 23.3 oz 18 oz 35 oz
Temperature Rating 0°F 0°F 0°F 0°F 0°F
Pocket Yes No Yes Yes No
Shoulder Girth (inches) 62" 66" 61" 60" 62"
Hip Girth (inches) 58" 57" 58" 55" 58"
Foot Girth (inches) 40" 41" 53" Not listed 40"
Shell Material 50D polyester ripstop MicroLite XP 20D nylon ripstop, DWR treatment 30D nylon, DWR treatment Ripstop nylon
Continuous Baffle No Yes Yes No No

Our Analysis and Test Results

Cosmic Down 0 Updates


Kelty has updated their Cosmic line since our test cycle with this winter bag. The new model was revised with trapezoidal baffles, a design intended to retain heat. The water-repellent coating is also now PFC-free, and the bag looks to have a weight increase over the old model, as well. Compare the two versions below; the model we tested is pictured first, followed by the updated Cosmic Down 0.

Click to enlarge
Click to enlarge

We're still linking to the previous model since it is still readily available. The content of this review from here on refers to that older version.

Hands-On Review of the Cosmic Down 0


There's no getting around it—this bag comes in at the bottom of the heap in nearly every one of our testing metrics. If the high price of premium down feathers is stopping you from enjoying cold weather camping, the Cosmic Down provides the necessary warmth but is a bear to carry around in the backcountry.

This bag is warm, lofty, and affordable, but also quite heavy.
This bag is warm, lofty, and affordable, but also quite heavy.
Photo: Matt Bento

Warmth


With 33 oz of 600 fill power duck down, the Cosmic Down is as warm as the super-lightweight Western Mountaineering Versalite, which costs hundreds of dollars more and is almost two pounds lighter. A draft collar and an effective draft tube help trap in heat, and so does the narrow foot box.

While not as comfortable for tossing and turning or stomach sleeping, a narrow cut reduces the bag's uninsulated space, keeping the user warmer. While this bag's shell fabric compromises weather resistance, and low fill power down adversely affects packability, warmth is one metric where this budget-friendly bag still does ok.

Light?...not exactly, but this bag does bring the warmth at a...
Light?...not exactly, but this bag does bring the warmth at a fraction of the cost of the competition. Not a bad deal for winter car camping.
Photo: Matt Bento

Weight


At 3.8 lbs, the Cosmic 0 is one of the heaviest bags in our review. This is because of the relatively heavy shell materials and the 33 ounces of duck down needed to achieve the same warmth as lighter bags with higher quality down.

While thick and durable, the 50-denier ripstop shell adds lots of weight. The fill weight to material weight ratio on this bag is about 1:1, where on the Western Mountaineering Versalite, it's 3:1. This bag has a relatively poor warmth to weight ratio and wouldn't be our first choice to lug into the mountains, but it's still lighter than many of the synthetic options out there. If you aren't hiking far, this Best Buy on a Tight Budget could be the ticket, especially if you're looking to save some Benjamins.

Comfort


A generous 62" of girth around the shoulders make it possible for back and side sleepers to snuggle in comfortably. The foot box is on the narrow side at 40", which helps maintain heat efficiently, but doesn't allow for much space to spread your feet around.

We feel that staying warm in bitterly cold winter conditions affects our comfort level more than room to spread out. But if you think you'll be spending hundreds of hours inside a sleeping bag this winter, you'll want something more spacious.

Packed Size


The 600 fill down is the least compressible fill material in our selection, but the Cosmic 0 packs down smaller than the warmest bags in our review, which contain more much more down and have roomier cuts.

The included stuff sack is enormous, but our testers managed to cram the Cosmic 0 down to a backpackable size with a compression sack. If you're primarily looking for a sleeping bag for car camping or short backpacking trips, packed size is less of a concern.

This sleeping bag will occupy quite a bit of space in your pack.
This sleeping bag will occupy quite a bit of space in your pack.
Photo: Jenni Snead

Features


The Cosmic 0 offers many features similar to bags two and three times its price. It has a full-length draft tube that hangs down over the zipper and keeps out wind and moisture. When fully zipped, the draft collar rests under the chin, but it doesn't have a cinch-cord. The hood is well insulated and kept our testers' heads toasty.

We feel that deeper hoods are generally more comfortable, as they aren't as claustrophobic feeling and it's easier to cover our faces when it's super cold out completely. The Cosmic 0 has four webbing loops intended to create a way to attach a sleeping bag using cordage (user provided). Our testers had various opinions on this feature.

A stash pocket on the outside of the bag is nice for quick access at...
A stash pocket on the outside of the bag is nice for quick access at night, but not very effective for keeping batteries or phones warm.
Photo: Matt Bento

Some thought that the tie-in points were helpful for staying on the pad all night, others felt they were unnecessary and inhibited them from sitting up in the bag to drink coffee or investigate curious nighttime sounds. Our lead tester accidentally got one of the loops caught in the zipper and almost ripped it off. Overall, we felt that this bag has one of the more "snaggy" zippers in our review selection. The Cosmic does not have a stash pocket, but the stuff sack will do the trick if you need to keep small items like batteries warm and contained inside the bag.

Photo: Matt Bento

Weather Resistance


This bag scored low in this metric because it wetted out through the stitching in our light rain test, and it was the only bag in our review that had this problem. It also absorbed the most water in our submersion test and took the longest to dry. Unlike many of its competitors, this bag doesn't have a DWR treatment on its shell fabric. The good news is that you probably won't be using your 0-degree bag in a rainstorm, and weather resistance is the least of your concerns if your sleeping bag is submerged underwater. You can always add a DWR treatment to your bag after purchase pretty easily (we like Nikwax products for this purpose).

Nonetheless, these tests illustrate that the Cosmic is more vulnerable to melting snow and condensation than the other bags. This problem can be alleviated by an adequate tent or bivy sack.

Without a DWR Treatment or a Goretex membrane, water can seep right...
Without a DWR Treatment or a Goretex membrane, water can seep right through the shell of a sleeping bag.
Photo: Matt Bento

Value


The Cosmic 0 will keep you warm in the low temps for a low price. For folks that only spend a few nights a year in the wintry backcountry, the cash savings are worth the extra weight. For what it is, it's a great deal.

Conclusion


If you're on a budget and don't want to miss out on some winter adventures because you don't have a warm bag, check out the Kelty Cosmic Down 0. Just make sure you have a good tent or bivy sack if precipitation is in the forecast. For a few short trips a year, the price can't be beat. Though heavy, this bag is plenty warm for sleeping temps down to the single digits, and lack of weather resistance is the main concern here.

Matt Bento