According to our research, the Cosmic 20 is one of the most popular 3-season sleeping bags. It's easy to understand why. It is one of the most inexpensive bags that's suitable for overnight backcountry travel. We know there are better bags out there, but the significantly higher prices just aren't worth it to everyone.
Performance Comparison
We gave the Kelty Cosmic our Best Buy Award not because it's the best sleeping bag out there, but because it's a suitable sleeping bag for backcountry overnights at an awesome price.
Warmth
The Cosmic 20 is filled with a blend of 18.2 ounces of insulation: 600-FP down (83%) and polyester batting (17%). Although the down is distributed throughout the bag, the synthetic insulation is limited to the underside of the bag to resist long-term compression.
With this blend, this bag receives an EN lower limit temperature rating of 19°F. In our tests, however, this rating seemed a little generous. We suspect most users will be happier down to a 25-30° limit with a good sleeping pad. This bag also features a passive neck baffle to prevent heat from escaping out the hood opening. Without this, the Cosmic would likely have an even harder time living up to its 20° manufacturer rating.
A rectangular flap inside the Cosmic serves as a draft collar to seal your heat inside the bag. Pictured here, it's the grey tube just above the orange fabric.
Weight
A size long tipped our scale at 2.63 lbs. This isn't particularly light compared to some premium down bags, but it stands up well against comparably warm synthetics. The Cosmic's biggest advantage is its weight relative to its cost. For its list price, it's hard to find an equally warm and low weight competitor.
Although the Klymit KSB 35 is priced similarly with a claimed EN lower limit rating that's comparable (21°F), in our test the Cosmic felt considerably warmer, roughly equivalent to 15° difference between their manufacturers' ratings.
The wide upper body dimensions of the Cosmic can be seen here. Bigger folks will likely appreciate them, but they could be drafty for smaller people.
Comfort
This bags 50-denier nylon fabric lining is unlikely to win any awards for softness. Compared to the sub-20-denier linings found on many high-end down bags, it feels coarse and stiff. This fabric, however, is far more durable than its softer competitors.
In terms of the dimensions and fit, the Cosmic is pretty spacious. Its 64-inch shoulder girth leaves it among the widest bags we tried. Like all mummy bags, however, it tapers toward the feet. This can be an issue for side or tummy sleepers who might prefer the hour-glass shape of the Nemo Riff 30. The Cosmic, in contrast, feels most similar to other loose-fitting, traditional, budget bags, like the Mountain Hardwear Lamina 30.
Packed Size
In a third-party compression sack, this bag packed down to 8.7 liters in volume. This leaves the Cosmic as one of the largest in our high-end sleeping bag review but smallest in our separate budget bag review. Along with weight, packed size thus appears to be one of the biggest differences between affordable and expensive bags.
The extra two liters in volume compared to the most compact bags is unlikely to be a big issue for most potential users. Bargain shoppers, however, should be aware that an additional seven liters separate the Cosmic from the bulkiest bargain bag, the Therm-a-Rest Saros 20. In this sense, 8.7 liters ain't bad.
Although most of the sleeping bags we test come with cloth (right) or mesh (left) storage sacks, the Kelty Cosmic does not. Be sure not to store it in the included stuff sack (center) or it may lose its loft.
An additional consideration for some will be that this bag only comes with a simple drawstring stuff sack that's ineffective at compressing it. To enjoy its reported minimum volume, you will need to buy a third-party compression sack that will cost you around $20. Unlike a lot of other bags, the Cosmic also doesn't come with a large storage sack for storing it when it's not in use.
Versatility
In our tests, this bag's ¾-length zipper was effective at venting excess heat on warmer nights. This zipper, however, ends 18 inches from the end of the bag which hampers the possibility of using it as a quilt. The passive neck baffle and decent hood give you a couple of ways to seal heat in better in colder conditions.
Like all down bags, the Cosmic's down insulation loses its ability to insulate if it gets wet due to the feathers clumping together. The 17% of the insulation that's synthetic fiber is also unlikely to be much help because its all located on the underside of the bag. If you plan to use your sleeping bag for particularly wet activities or environments, the Nemo Kyan is a fantastic choice within the same price range.
Features and Design
In the latest versions of this bag, Kelty has added a convenient stash pocket that's great for keeping a phone or headlamp close by. In addition, the fabric adjacent to the zipper is now a burlier nylon weave. This is helpful because it adds stiffness to keep the fabric to keep it out of the zipper's teeth and ensures that if the zipper does snag it's unlikely to tear.
The fabric covering the rest of the bag is also a higher denier than most ultra-premium bags. On the one hand, this is bad because it's heavier and coarser, but on the other its great because the added strength means you don't have to baby the bag as much.
In the latest version of the Cosmic a small stash pocket was added. It's a great place to keep your phone or headlamp handy.
Best Applications
The Cosmic leaves its options open. It isn't designed to be great in a single area like some other bags are for weight or comfort. This means there aren't many backcountry applications the Cosmic isn't suitable for. If you do specialize in a single activity, however, there may be a different bag that's designed especially for you.
Value
While the Cosmic provides only average performance in several areas, its price is excellent. Listed at only $170 MSRP, it is a great deal for a legit backpacking bag. Although it weighs a little more and doesn't pack as small as the top-performing bags, you can use the $300 you save to cut weight and bulk from other pieces of your backcountry kit.
The Kelty Cosmic's reasonable price and burly shell fabric mean you don't have to worry about it as much as you would a pricier, more delicate, bag.
We feel the same about a closer comparison with the more expensive REI Igneo 25. To us, the modest benefits of the Igneo aren't worth the extra $100 it costs. Dollar for dollar, the Cosmic really is a great value.
Conclusion
The prices of lots of backcountry gear can be pretty shocking. Charging $500+ for a simple bag made of nylon, feathers, and a zipper is sure to sound like highway robbery to many folks. For those, the Kelty Cosmic 20 serves as a reasonable compromise. Although it doesn't receive the highest scores in warmth, weight, or comfort, its performance is more than adequate for most backcountry applications. We believe the benefits of a high-end bag are worth the added cost to serious backpackers, but for everyone else, the Cosmic provides acceptable performance at a more reasonable price.
