How to Choose Sleeping Bags for Backpacking
Kelty Cosmic Down 40 Sleeping Bag
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Great for warm-weather backpacking, the 2-season Kelty Cosmic Down 40 sleeping bag features lofty 600-fill-power DriDown™ insulation that defends against moisture and still compresses small.
Shop similar productsKey Details
Fill
600-fill DriDown
Temperature Rating (F)
40 degrees (F)
- Ripstop polyester creates a smooth yet durable shell; polyester taffeta lining breathes for comfort and feels great against skin
- 600-fill-power DriDown has a water-resistant finish that allows down insulation to resist moisture, dry fast and maintain loft
- 60 in. dual-slider locking zipper with antisnag design and draft tube to hold in warmth
- Thermal comfort hood has drawcords of differing widths at head and neck for easy identification and adjustment in the dark
- Off-set construction provides maximum warmth without cold spots
- Full draft collar drapes comfortably over neck and shoulders, sealing out drafts
- Natural-fit footbox provides plenty of room so feet don't feel scrunched
- Stuff sack included
Imported.
Temperature ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth, since many different factors contribute to your comfort while you sleep. Backpacking bags are typically rated for temperature according to an independent testing protocol—currently International Organization for Standardization (ISO) 23537, though some older items followed European Norm (EN) 13537. Testing is based on a person wearing one base layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38.
Each bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
View all Kelty Backpacking Sleeping BagsEach bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
| Best Use | Backpacking |
|---|---|
| Tested Lower Limit | 40 degrees (F) - EN |
| Tested Comfort | 48 degrees (F) - EN |
| Temperature Rating (F) | 40 degrees (F) |
| Temperature Rating (C) | 4 degrees (C) |
| Shell | 50-denier ripstop polyester |
| Zipper Location | Right |
| Insulation Type | Down |
| Water-Resistant Down | Yes |
| Fill | 600-fill DriDown |
| Lining | 50-denier polyester taffeta |
| Sleeping Bag Shape | Mummy |
| Stuff Sack Size | 7 x 12 inches |
| Stuff Sack Volume | 7.6 liters |
| Gender | Unisex |
Buying Advice
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Most Helpful Favorable Review
Fantastic value
Ayuill9 years ago
This is a great bag that lofts well and holds up to its 40f claim. Just a couple items of note. This is a 600 fill bag but the draft guard and the bottom of the foot box are synthetic. The tag claims 75% down minimum to 25% feather but to feel it I'd say it's a little higher, which is a good thing. Wish that the 75% was advertised somewhere prior to purchase, would've liked a higher target.
Only questionable thing is tag claims the fill weight is 10.2 ounces but the Kelty website says 12 ounces and REI says 13. Don't think it should be an issue but idk what Kelty is doing there. I also wonder if the 10.2 ounces includes the synthetic fill or is just the down, the bag doesn't specify. Would've liked that almost two-three additional ounces of down.
For the price you won't find better for late spring through early fall camping. Don't forget that Kelty also has a pretty broad lifetime warranty.
Ayuill
Silver Spring, MD, United States
36 people found this review helpful
Most Helpful Critical Review
Lightweight, very packable, but not warm
medbow8 years ago
I have used this a few days now in Colorado (early June 2017). So far I here is what I have experienced:
Pros:
+ Lightweight
+ Affordable
+ Water resistant down is nice
+ Very packable compared to my synthetics
Cons:
- Not warm --> I am from the mountains in Wyoming and am used to cold temperatures, but this bag did not do the job down in Northern Colorado. It got down to about 35-40F at night (early June 2017), and I was pretty chilled even with a light blanket. I am tossing back and forth returning it for a 20F or purchasing a liner.
- I am 6' 1" ~170 lbs and this bag is pretty tight.
medbow
11 people found this review helpful
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Ayuill
Silver Spring, MD, United States
Fantastic value
9 years ago
This is a great bag that lofts well and holds up to its 40f claim. Just a couple items of note. This is a 600 fill bag but the draft guard and the bottom of the foot box are synthetic. The tag claims 75% down minimum to 25% feather but to feel it I'd say it's a little higher, which is a good thing. Wish that the 75% was advertised somewhere prior to purchase, would've liked a higher target. Only questionable thing is tag claims the fill weight is 10.2 ounces but the Kelty website says 12 ounces and REI says 13. Don't think it should be an issue but idk what Kelty is doing there. I also wonder if the 10.2 ounces includes the synthetic fill or is just the down, the bag doesn't specify. Would've liked that almost two-three additional ounces of down. For the price you won't find better for late spring through early fall camping. Don't forget that Kelty also has a pretty broad lifetime warranty.
Yes , I recommend this product
Pushenmyluck
Port Orchard, WA, United States
Weight and size means everything
8 years ago
I purchased this bag a month ago and I was not disappointed. I blew the side out of my other sleeping bag washing it, in a pinch I purchased this one as a temporary replacement. I sleep hot so this bag was more than sufficient at 50 degrees outside. I would recommend a silk liner if you expect between 30 and 40 degrees. As for the size I was able to easily put it in the bag pouch at the bottom of my pack. Weight is comparable to my $400.00 20 degree bag which everybody knows weight is everything on a back country hike. All in all for the price, temp rating, and weight this would make an excellent backup bag. If you're just getting into hiking I would really recommend this bag as a primary!
Yes , I recommend this product
MSalas
Virginia
Good bag, Great Value
8 years ago
Purchased this bag several months ago. Have had it out on the trail a few times now. Performs great. No issues so far. Had it in low 40's high 30's. I slept just fine. I do use a bag liner that adds 5 or 6 degrees to the rating. I'm 6'3" 200lbs. I bought the long and I'm comfortable in it. I sleep pretty hot so this is my go to bag unless temps are going to drop into the 20's Pros: compresses well, light weight, plenty of room, affordable price. Cons: haven't found any at this point. Very happy overall. This bag does what it says it will do.
Yes , I recommend this product
Brad47
Ohio
Great Summer Bag
7 years ago
I bought three of these - one for me and two for my kids - to do summer camping in NM and CO. After hauling my old 6lb down bag for years, this bag is a revelation. No doubt it is translucent, but it is warm down to 40oF for me and the weight can't be beat. My kids had the same experience - very comfortable and warm. However, this is a summer bag. If you are going to regularly encounter 40oF or below weather, there's not enough margin here, especially if you get into a hypothermia situation. I use this as my summer bag and use old faithful whenever the forecast is for low 40's or below. And yes, you need a foam pad. No sleeping bag insulation will work when you compress the fill with your body weight!
Yes , I recommend this product
Miked5459
New Jersey, United States
Great Buy!
8 years ago
Had the opportunity to try these out last week on an overnight in North Jersey. The bag is very light and incredibly easy to pack. Pretty soft and comfortable. Overall very satisfied with the product. Only two minor knocks. One is the zippers could be a little easier to zip. The other is not really a knock, just a warning...the bag is rated at 40 degrees and it works to 40 degrees. I slept in under armor and socks and the outside temp was at 40. Not cold, but not toasty either, so if you're going colder get a liner.
Yes , I recommend this product
medbow
Lightweight, very packable, but not warm
8 years ago
I have used this a few days now in Colorado (early June 2017). So far I here is what I have experienced: Pros: + Lightweight + Affordable + Water resistant down is nice + Very packable compared to my synthetics Cons: - Not warm --> I am from the mountains in Wyoming and am used to cold temperatures, but this bag did not do the job down in Northern Colorado. It got down to about 35-40F at night (early June 2017), and I was pretty chilled even with a light blanket. I am tossing back and forth returning it for a 20F or purchasing a liner. - I am 6' 1" ~170 lbs and this bag is pretty tight.
No, I do not recommend this product
Brogi
Phoenix, AZ, United States
Unbeatable at the price point
8 years ago
Just got back this morning from a beautiful car camp in Prescott National Forest, elevation 6,200 ft. Springtime in Arizona is very diverse and offers amazing outdoor opportunities that can range from 15 degrees to 100. I'm a big guy (6'3 270) and not used to camping, so this was my first sleeping bag purchase. That being said, I was very reluctant to go straight mummy in fear of "sleeping bag claustrophobia." So I found this bag w/a slight relaxed mummy design via great reviews. I went with the 40 b/c I wanted something that could handle the AZ mild cold while also maintaining some degree of use for our warmer climate. I was going for the best all around bag knowing full well that I'll most likely have to have two bags. Re: this review, I've noticed that there don't seem to be too many reviews by us big guys for temp ratings and how they hold up; this one is for the larger folk and "warm sleepers.." The temp was at 40 when I entered the tent (REI Half Dome 2 Plus -- amazing). I had two pair of semi-thick smart wool socks on, a pair of Tru-Spec pants, undershirt/long underwear top/fleece outer, and a standard winter hat (I'm working on the layers, they're expensive). MOST importantly, I was using a Thermarest Basecamp bed roll -- if you're unfamiliar, from what I understand, most bag temp ratings are scaled using a very similar bed roll w/R-Value of 5. It's very important you take note of this b/c it was a lifesaver. Being the novice that I am, I woke up at 2:30am freezing cold b/c I didn't have the bag zipped up fully, haha. So I zipped her up as far as I could and stuffed a sweatshirt in the awesome head pocket that made a perfect pillow. I also pulled my hat down over my face so that virtually no skin was exposed. Let me tell you, if you are worried about the mummy design, don't. I found myself wishing the bag were even tighter, haha. This isn't a knock, however, b/c I truthfully find the dimensions of the bag perfect for me (I bought the "Long" model). Now, maybe others can shed some light on this next point b/c Im not sure it's a legitimate criticism, but I found it annoying trying to fully zip a right-side zipper; I felt like I couldn't get it fully zipped. After these adjustments, though, I fell asleep easily. I still consciously felt cold while I was asleep, but it wasn't b/c of bag failure.. when I woke up at sunrise (6am) it was 28 degrees. I'm guessing that through the night it was reasonable to assume the temps were mid to low 20's. Therefore, I am a fierce advocate the 40 degree rating is solid. Add a bag liner and proper layers, and it's a 30 degree bag for us warm folk. All-in-all, very pleased with this bag at this price point. Kelty really did a great job with the synth/600 down blend. And the icing on the cake: the thing cinches down to a tiny size and weighs incredibly low compared to it's competitors. You can't go wrong with this bag; I would/will buy Kelty again. Hope this helps...
Yes , I recommend this product
gmsp
Dover, DE, United States
Lite & comfortable
9 years ago
I used this for out hike on the Chilkoot Trail in Alaska. I stayed comfortable with the temperatures in the lower 40's. Compressed down for easy packing & lite weight.
Yes , I recommend this product
MACK
Barrington Hills, IL, United States
light, well made, but dress warm for 40s
8 years ago
I JUST USED IT ON MY HIKING TRIP TETONS MOUNTAINS WY. IT IS JULY, BUT AS USUAL TETONS ARE COOLER (CREST TRAIL CLOSED WITH 5-6" OF SNOW). DAY TEMPS WERE 80-70S DEPENDING ON ELEVATION, NIGHT PROBABLY STARTING 60S DROPPING TO 50S, AND EARLY MORNING <50. I SLEPT IN LONG JOHNS, SWEATER AND 4-6 AM GOT CALLED. STILL GOOD SLEEPING BACK SINE LIGHT, PACKABLE, BUT IF YOU PLAN TO SLEEP WITH TEMPS ~40F MAKE SURE YOU ARE DRESSED. SLEEPING BAG OTHERWISE IS WELL MADE, ONLY MISSING THE POCKET TO STUFF IT WITH SHIRT TO MAKE A PILLOW.
Yes , I recommend this product
BenUpNorth
Minnesota
Packs small, decent warmth
7 years ago
I’m a big(ish) guy, 6’2” and 240 lbs, and it fit really well. Long enough so the hood was a good fit over my forehead and yet my feet weren’t squished. I suffer from an ex-athlete body with broader shoulders than most, but I found this bag to fit nicely across the chest and shoulders. Enough wiggle room in the knees too. When I rolled on my side during the night, it rolled with me so I didn’t spin inside it. I’m a fan of the rip stop type material under the zipper. I haven’t had an issue with the zipper getting caught on the fabric and don’t foresee an instance where that would happen (as long as I don’t do something stupid and zip it haphazardly). It compresses down quite small and is pretty light weight in my pack. The warmth is the only reason I wouldn’t give it 5 stars. The 40 degree rating is close, but still a bit chilled. First trip was end of May in central Minnesota with overnight low of 42. I had a Therm-a-Rest Basecamp pad under me and had to wear my long johns in the tent. If I add a liner, I’m sure I can use this bag down into the upper 30’s.
Yes , I recommend this product
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