Kelty Cosmic 20 Review

According to our research, the Cosmic 20 was one of the most popular 3-season sleeping bags of the last decade. Recently, a new version was released. After thorough testing, we're sad to report that many of the new changes are for the worse. The proportion of down-to-synthetic insulation decreased from 83% to 75% and the quality of the down fell from 600 to 550 fill-power. These changes result in a new version that is heavier, bulkier, and less warm than in the past. Fortunately, the price also dropped. Shoppers in 2021 should be aware, however, that today's Cosmic 20 is not the same award-winning bag as a few years ago.

Performance Comparison

The new (left) and old (right) versions of the Kelty Cosmic Down 20. The new version lags behind a few cheaper competitors. The old version was a best-in-class bargain, consider picking one up if you can find one.

Photo: Jack Cramer

Warmth

The Cosmic 20 is filled with a blend of 16.4 ounces of insulation; 75% of this is 550-FP down and the remaining 25% is polyester batting. The down is distributed throughout the bag, while 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 21°F. In our tests, this rating seemed a little generous. We suspect most users with a good sleeping pad will be happier down to a 25-30°F limit. 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°F manufacturer rating.

The 21F lower limit temperature range is ideal for cold sleepers or brisk nights in the spring and fall.

Photo: Jack Cramer

Weight

A size long tipped our scale at 2.83 lbs. This is kind of heavy compared to some premium down bags, and it is average relative to similarly warm synthetics. The Cosmic's biggest advantage is its weight relative to its cost. For its list price, you do get a respectable warmth-to-weight ratio.

Although we've tested other affordable bags with similar EN lower limit ratings, in our tests the Cosmic felt like one of the warmest in its price range.

The hood cinches down tightly when you want to trap heat inside. However, we were unimpressed with the long, coarse hood drawcord.

Photo: Jack Cramer

Comfort

This bag's 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, feels far more durable than its softer competitors.

In terms of the dimensions and fit, the Cosmic is pretty spacious. Although its shoulder girth dimensions were unreported when we published this review, it feels like a generous 60+ inches. Like all mummy bags, however, it tapers toward the feet. This can be an issue for side or tummy sleepers who might prefer an hour-glass shaped or zipperless design. The Cosmic, in contrast, feels most similar to other loose-fitting, budget, mummy bags.

One of the primary benefits of down insulation compared to synthetics is smaller packed size. The fill-power of the Cosmic's down is only 550, so its advantage over synthetic insulation is much less than premium down.

Photo: Jack Cramer

Packed Size

In a third-party compression sack, this bag packed down to 9.2 liters in volume. This leaves the Cosmic as one of the largest in our high-end sleeping bag review but better than average among budget-focused sleeping bags. Along with weight, packed size is one of the biggest differences between affordable and expensive bags.

Among budget bags near the same price point, we prefer generally other synthetic models for a range of performance characteristics including weight and comfort. The one area where the down insulation of the Cosmic is clearly superior though is packed size. So if packed size is important to you, the Cosmic could be the right choice.

When it comes to stash pockets, we prefer that they're located inside rather than outside the bag. This ensures that the batteries in your electronics stay warm and holding a strong charge.

Photo: Jack Cramer

An additional consideration for some will be that this bag only comes with a simple drawstring stuff sack that's ineffective at compressing it fully. To enjoy its reported minimum volume, you will need to buy a third-party compression sack that will cost you around twenty bucks. 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. We recommend hanging this bag in a closet instead of storing it in its stuff sack when 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 harms the ability to use it as a quilt. The passive neck baffle and decent hood give you a couple of ways to seal in heat 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 25% of the insulation that's synthetic fiber is also unlikely to be much help because it's all located on the underside of the bag. If you plan to use your sleeping bag for particularly wet activities or environments, there are several great synthetic options in the same price range.

We're not big fans of the Cosmic's U-shaped zipper slide because it's kind of finicky. However, we are big fans of the stiffer strips of blue nylon fabric next to the zipper because they reduce snagging.

Photo: Jack Cramer

Features and Design

The latest version of this bag includes a convenient stash pocket on the inside that's great for storing a phone or headlamp. In addition, the fabric adjacent to the zipper is now a burlier nylon weave. This is helpful because it adds stiffness to 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 many ultra-premium bags. On the one hand, this is bad because it's heavier and coarser, but on the other, it's great because the added strength means you don't have to baby the bag as much.

To achieve its 21F temperature rating, the Cosmic includes a cozy flap of blue, insulated fabric near the neck to prevent heat from escaping out the hood.

Photo: Jack Cramer

Value

While the Cosmic provides only average performance in several areas, its price is excellent. It represents a good deal for a legit backpacking bag. Although it weighs a little more and doesn't pack as small as the top-performing bags, you could use the hundreds of dollars you save to cut weight and bulk from other pieces of your backcountry kit.

Conclusion