Kelty Cosmic 40 Sleeping Bag Review

Poised to provide an aggressive balance between price, weight and performance, the Kelty Cosmic 40 is a lightweight down sleeping bag that retails for just $130. This is my review:

The Cosmic 40 from Kelty is mostly a traditional mummy style sleeping bag, meaning it sticks close to the body and tapers at the feet. The shape is slightly modified to provide a little extra room at the shoulders, hips and feet without adding significant weight. It has a long, full length zipper with integrated anti-snag draft collar and a second zipper at the bottom of the bag to act as a large adjustable vent. There is a small chest pocket, a handy hood cinch and it comes with a lightweight stuff sack to help aid in packing it down. It is constructed from 50 Polyester taffeta for the liner, while the outside is 20D taffeta nylon. It is coated with a light DWR finish and is filled with 11.2 ounces of 600 power fill DriDown. It weighs 1 lbs 12 oz.,compresses to about 7″ x 13″, and retails for $130.

What I liked

In my eyes, an exceptionally comfortable sleeping bag is more of a must than a consideration. I’m a finicky sleeper so I can’t have my sleeping bag causing me grief. The search for a compliant sleeping bag often brings me back to the Kelty Cosmic series, with the 40 being no exception. Simply sliding inside the Cosmic 40 brings me down to a relaxed and lethargic state, with the soft billowy walls trapping me willingly inside. The chosen materials of soft and silky polyester for the inner feels exceptional against the skin. It is soft, forgiving, and slides effortlessly against the skin as I move about. It handles moisture really well too, avoiding feeling clammy when it is really humid out or if I start sweating inside. It is roomy enough that I can toss and turn (being a medium sized guy) and I have just enough room to spread my feet apart, while never feeling too cramped up. It is still a mummy style bag, so there is no real splaying to be had without completely undoing the zipper, but even so I always felt cozy and at home inside, never trapped or overly restricted.

The sleeping bag is also relatively warm, holding true to its EN rating of about 37 degrees. It has managed to keep me completely warm and toasty to just above freezing in nothing but a standard t-shirt and under layer. Below that, the cold does start to seep through but a decent thermal layer and camp socks could see this bag used down to about 30 degrees, if paired with the proper sleeping pad. The draft collar does a pretty good job of blocking out leaking air, and the foot compartment is insulated well enough that cold toes were never an occurrence. The 600 power fill down does a great job of providing both warmth and heat regulation, with it never really getting too hot when used above the 40 degree rating either. The second zipper certainly helps with that as it can unzipped from the foot all the way up to the chest, acting as a small or huge vent when needed. Also, the sleeping bag can be unzipped completely, making for a nice makeshift blanket, even if the shape isn’t ideal.

As far as weight goes, given the price and temperature rating, I was very impressed here. Weighing in at 1 lb. 12 oz., the Cosmic 40 is one of the lightest full sized sleeping bags in the price range. While it isn’t the lightest sleeping bag on the market, it is still what I would readily consider light-weight and well within the bounds of comfort that I strive for on the trail.

The weight savings also come with space savings, which brings us to size and packability. It shrinks down to about 7″ x 13″ with the included stuff sack, and I was able to get it even a little smaller with a dedicated compression sack. It fits well into my 48 liter bag overnight bag, still saving plenty of space for an ultralight tent and kit. It’s compact enough that I prefer to keep it stashed away in my car (generally stored lofted in a mesh sack for long term use) as a just-in-case bag, for when snowy conditions unexpectedly blow in while I’m on the road.

Durability is also pretty good, with the quality as a whole being much better than one would expect. The materials have held up great to repeated packing and unpacking, with it being tested in temperatures in a range of 15-80 degrees. The fabric and down lofts back up effortlessly time after time(a quick shake helps) and so far I’ve had no snags, tears, or abrasions on the fabric. The stitching quality is pretty good also, with most of the seam lines being very consistent with only a couple minor stray strands popping up at the end of a run. So far, the tiny down feathers inside haven’t been working their way out either.

Smaller details like the chest pocket (great for keeping a phone warm and functioning in the cold), a robust anti-snag zipper backing and high quality zippers are really appreciated.

What I didn’t like

While generally very comfortable, I did miss the lack of a full perimeter draft collar around the hood and neck. There is a nice thick collar on the hood itself that runs around the face and forehead, but nothing that lines the neck and chin. Instead, it’s just a very basic cutoff point. It’s actually rather comfortable but a draft collar here would go a long way, especially when helping to seal out heat when the temps drop to the lower end of the temp ratings.

The material does lack ripstop (an embedded nylon mesh that helps keep tears from spreading), so if a tear does occur it should be repaired quickly before it worsens. Thankfully in a sleeping bag this is rarely a big issue and a quick patch kit usually suffices if a tear does occur.


The kelty Cosmic series has always provided an excellent balance of price and performance. Somehow, with the latest revisions, Kelty has managed to improve that balance even further. The fabrics feel fantastic, the durability is good, and it packs down to an impressively small size. There really is no sleeping bag on the market that in my mind compares to the quality, weight and warmth they provide at this price. At just 1 lb. 12 oz., it’s a sleeping bag that I can recommend for just about anyone, shy of the most dedicated ultra-lighters.

Highly Recommended

For more information on the Kelty Cosmic 40, check out our Amazon Affiliate Link here. This helps us out.

For information on our rating system and our testing procedures, check out our About us/ Contact us page.

I want to extend a huge thanks to Kelty for providing this product for review. We couldn’t do it without their help.

Our full disclosure can be found here. Thanks as always for reading! Don’t forget to follow our blog for future updates and reviews (link on the right also).

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