Kelty Cosmic Down 20 Sleeping Bag Review

Bottom Line

The Kelty Cosmic Down 20 (men’s / women’s) is a comfy, affordable, no-frills mummy sleeping bag. Thanks to fluffy down insulation, this one has a stellar warmth-to-weight ratio, making it a standout on our best sleeping bags for camping guide. Senior Gear Analyst Ian Krammer used this bag to stay warm for 14+ chilly nights when car camping high in the Colorado Rockies, but he’s also backpacked over 150 miles with it, including a 30-mile loop in Utah’s Canyonlands National Park.

We love the smooth, cozy interior, and the down heats up impressively fast. The mummy design, with a narrow footbox and hood, traps heat efficiently. Kelty uses highly water-resistant and quick-drying nylon for the exterior, perfect for damp and humid conditions. We also love its large stash pocket – which many mummy bags don’t offer – for easy access to essentials.

However, this bag’s narrow fit might not be the best if you prefer more room to spread out. It’s also a bit on the heavy side for a down bag. We don’t mind for car camping, but it’s a bit much for long-distance backpacking versus other down bags. Additionally, there’s a large price gap between the men’s and women’s versions, with the latter costing significantly more. For campers looking for reasonably priced warmth in an ultra-portable package, the Cosmic Down 20 is a stellar bang for your buck.

Comfort

The Kelty Cosmic Down is a comfortable mummy bag with cushy fabric, thick draft tubes, and a highly adjustable hood. We’re fond of the plush 20D nylon taffeta liner fabric for a super smooth and soft feel. Combined with the thick, soft draft tubes along the side zipper and neck, this bag is easy to sink into after a long day of playing outside.

The slim-fitting mummy shape is just roomy enough to switch from back to side fairly, and the ergonomic, rounded footbox means we were able to move our feet easily without issue. We also like that the hood is highly adjustable thanks to a single, simple cinch cord. It’s spacious for most backpacking pillows, with plenty of room to bury our heads as well as sit up with the hood still on.

However, if you’re a car camper or are staying mostly in the frontcountry, the biggest downside of the Cosmic Down 20 is its mummy shape. This design is awesome for conserving maximum heat in the backcountry, but it’s not as cozy compared to a big, rectangular bag. If you tend to move around a lot when you sleep, or you’re a belly sleeper, the mummy design can feel constricting. That said, if you’ll be backpacking too, or simply prefer a snugger fit, the Cosmic Down 20 may be exactly what you’re looking for.

Warmth

The Kelty Cosmic Down 20 expertly balances weight and warmth. Our testing finds the 550-fill down insulation kept us toasty warm to 30°F, but it weighs only two and a half pounds for the men’s and three and a half pounds for the women’s. We prefer the 20° for its versatility, but it comes in a 0° version and 40° version for any season. This bag kept us cozy and comfy during a four-day car camping trip to 12,500’ Stony Pass in Colorado’s San Juan Range, where we dealt with rain, strong wind, and glaring sun. It’s also done the job on a bone-dry backpacking trip into a remote part of Canyonlands National Park in early December.

Kelty keeps weight to a minimum using down feathers and a lightweight but hardy 20D nylon material for the inside and outside. This construction offers tons of warmth, but still rolls up very small compared to bags made with synthetic fill and heavier materials. The fairly snug mummy design also reduces excess material. It really shines between 30°F and 60°F. That said, if it’s too warm, simply unzip the two-way zipper for more breathability.

It’s worth noting the women’s bag is notably more expensive because it has a higher fill weight compared to the men’s. The men’s Regular has a fill weight of 16.4 ounces, whereas the women’s has 29.06 ounces – so the women’s weighs and costs more, but will feel warmer through the chest and hips than the men’s.

Down requires a bit more maintenance to retain its warmth than synthetic bags. To maintain its warm and fluffy properties, you’ll need to occasionally wash your bag with down-specific detergent, store it long-term in a loose mesh bag, and keep it dry to maintain its properties. These are easy steps, but this may be a downside if you won’t be backpacking, or if you’re only car camping a few times a year and prefer simplicity.

Packed Size

The Kelty Cosmic Down 20 shrinks down the smallest of any model on our guide. It weighs only 2 pounds, 7 ounces for the men’s and 3 pounds, 4.8 ounces for the women’s – so it’s a great choice for both backpacking and limited trunk space. The down insulation and thinner, lighter nylon material directly contributes to the incredibly small packed sizes – a mere 8 by 13 inches for men’s and women’s.

But if you’re looking for the lightest gear, these specs might miss the mark. Folks who want small, ultralight gear for both backpacking and car camping may want to keep looking. If that’s you, check out our backpacking sleeping bags list to reduce your pack size and weight even further.

Since the feathers can get mashed and broken over time, you’ll want to keep the Cosmic Down in a mesh storage sack when not in use. This keeps the insulation light and fluffy and prolongs the quality, performance, and durability of your bag over time. Unfortunately, Kelty does not include this, so we highly recommend picking up a large, breathable mesh sack for long term storage.

Features

The Kelty Cosmic Down 20’s feature set is simple and familiar. The ergonomic mummy design is slim with a cushy hood just-roomy-enough footbox. Its water-resistant shell offers added protection against condensation and wet conditions. The two-way zipper is handy for ventilation. Not all mummy bags have an internal stash pocket, but we love that the Cosmic Down 20 does – and it’s zippered. This pocket is a bit shallow for larger phones, but it works well for keeping a chapstick or headlamp close at hand without items falling out and disappearing into the folds of your bag. 

However, that’s all there is to this bag. It doesn’t have a pad attachment sleeve, oversized hood, additional pockets, a mesh storage bag, or fancy bells and whistles. That said, the basic design works for us – it’s unsurprising, but also warm, comfortable, and packs small.

Should You Buy the Kelty Cosmic Down 20?

The Kelty Cosmic Down 20 is a great 3-season bag for car campers, occasional backpackers, and those on a budget who still want a quality down bag. Its combo of affordable price and a high warmth-to-weight ratio makes it a great choice if you want a good value without compromising warmth. The mummy-style design helps retain body heat, and a durable, water-resistant shell ensures protection against humidity, making it perfect for car camping in a variety of conditions. We also appreciate the small packed size, large, cushy hood, snag-free zipper – and the zippered stash pocket to corral little items. The Cosmic Down proves that a quality down bag doesn’t have to break the bank.

However, it isn’t the best for folks who like to spread out, as the narrow mummy fit may miss the mark, especially if you’re exclusively car camping. The weight is reasonably low for car camping and shorter backpacking trips, though it’s not suitable for longer-distance backpackers counting every ounce. Additionally, this bag has a very large gap in price – as well as weight – between the women’s bag and the men’s bag. That said, the women’s has more down. Despite these drawbacks, the Kelty Cosmic Down 20 remains an excellent choice for car camping or a few days out on the trail, offering great warmth and cushy comfort in a durable design that packs small.

What Other Camping Sleeping Bags Should You Consider?

See our guide to the best camping sleeping bags and find out how the Kelty Cosmic Down 20 compares to the others. And while you’re here, consider these other top picks:

Mountain Hardwear Bishop Pass 15 Review: The Bishop Pass 15 is another mummy bag made with high-quality down and features excellent packability. It weighs half as much and is warmer than the Cosmic Down but costs more.

NEMO Disco Endless Promise Review: The Disco shares the same quality down insulation and cozy, warm feel as the Kelty Cosmic Down 20. However, it’s significantly pricier, less warm, and weighs less than half as much.

The North Face One Bag Review: The North Face One Bag is pricier, lighter, and offers three temperature ratings. This bag is perfect for campers willing to pay a premium for awesome versatility.