What is Your Sleeping Bag’s REAL Temp Rating?

Are Sleeping Bag Ratings a Lie? Sleeping Bag Temperature Ratings are an important part of finding the right sleeping bag. If your bag isn't warm enough it can be dangerous. But there are no laws requiring brands to adhere to any specific standard. Which makes me wonder. Are Gear Companies Lying To Us?

The Quilts and Sleeping Bags Mentioned in this Video:

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[MyLifeOutdoors]

The Quilts and Sleeping Bags Mentioned in this Video:

[Gemini-bg]

Engineer here: A proper test would be to put a couple of gallons of water, in a container at 98.6F in the bag and measure how much time it takes to get to a lower temperature of your choosing. (say, 70F). The bags that take longer insulate better. Such a test will measure the actual heat flow and thus the insulative performance, not distance of a material ("loft") which might not be consistent.

[bustercrabbe]

I was taught in my Appalachian Mountain Club winter camping school in the 1970s three things about any winter sleeping bag: 1. they are only warm for a finite amount of time, six to eight hours; 2. they are always cold in the foot box (foot area); and 3. you always deduct 10 degrees from the rating. And this sage advice holds true even today.

[averagedoes]

The loft measurement in inches is an inherently flawed concept (which should be obvious because if it was that simple then EN and ISO would use that method). Construction material matters as well. Trapped air alone doesn't create insulation, air movement within the material is critical as well. This is why closed cell foam would be a better insulator than an un-insulated air pad of the same thickness, and the same reason why a wall space filled with fiberglass has a higher R-value than an empty wall space (both have the same "loft" of 3.5"). So the type, quality, and density of the fill material is going to matter quite a lot, and that's without even getting into baffle construction, seams, draft, etc.

[Thalanox]

So, what I'm picking up from this is that once you get into the camping/outdoors hobby and buy enough equipment to finally know what you're doing and keep at it, you've spent so much money on equipment that turned out to be duds that you have to try to monetize the gear that you wasted your money on, and making gear review videos is one of the more common ways to do that.

At least later generations of curious campers and research junkies are going to have an easier time of it thanks to your sacrifice. Your efforts are appreciated.

[markcummings]

Great video! Other considerations that are assumed in both testing Standards-
-Test occupant is (Fit) Male, (supposedly female anatomy sleeps colder)
- Occupant has some form of head cover; Hat, Beenie
- Occupant is well fed
- Occupant is not wet
- No wind
- Bag/Comforter is properly sized ( undersized bag insulative values will be compromised if baffles are being “squished”

[asmith]

The local gear shop told me I only needed a 20 degree F bag for where I go camping. I bought a 0 degree F. Good call on my part. Down into the teens it is still nice and warm. Buy a good brand from a reputable source and add at least 10 degrees to the rating. I will say that if you actually live outdoors for an extended period you become acclimated and will in fact become comfortable at something closer to the posted ratings. I was in the Army for 4 years and we would be on field exercises for up to a month at a time where we slept outdoors 24/7, no tents, no heaters, etc. You find yourself able to wear less and less over time to remain comfortable. Good stuff costs money, you get what you pay for in some things. I'll pay to stay warm at night! Good video.

[TheGolleum]

It is great you are spreading this information. I worked at a camping store and every customer came in saying they had been lied to before about what they needed out of their sleeping bags. Even the largest camping store in my country didn't adequately explain what customers needed to consider to pick the right bag. I never had any customer come back and say their bag was too hot or not warm enough when they were given the proper service. It just sucks that they needed the service and couldn't pick the right one off the rack because of the labeling

[gemcarpetcare]

Found out 30 years ago take the temp rating of the bag and add 30 degrees to it and you are about right.

[ChrisOUTEC]

Sleeping bag loft measurements:
1) 1.875" Loft: "Marmot Phase 30", 42°F Comfort & 33°F Limit, ISO ratings
2) 2.125" Loft: "Marmot Phase 20", 33°F Comfort & 22°F Limit, ISO ratings
3) 3.5" Loft: "Western Mountaineering Antelope MF 5°", 14°F Comfort & 1.4° Limit, EN ratings
Great work as usual -- thank you!

[septemberamyx]

As a former aircrew member who went through survival school, and a former NICU RN, an acrylic liner is the thing that will keep your heat, period. It will keep you from dying, and is the primary and essential item for attempting to stay warm in any camping bedding.

[jakebrown]

I returned a Big Agnes Sidewinder for this very reason. It was a '20 degree' bag and man. It was SO cold, even when using a 4.3 R Value pad. I got a 30 degree EN rated Nemo bag instead and it was just as warm as the '20 degree' BA bag. And now I have a 30 degree Katabatic quilt and it's even warmer than both of them!

[Bohonk]

My old North Face 32° bag I bought mid 1970s has the same loft as a 0° bag bought today.

[haroldmarenger]

Interesting article. I am looking for a new sleeping bag, and this article gives me food for thought. My takeaways from this article are: 1) the insulation needs to create enough loft for the environment you are in, trap air to minimize circulation and retain heat; 2) have an inner layer material (that’s next to your body) that allows enough heat transfer to the loft to keep you warm while not drawing too much heat away from your body; 3) have an outer layer that effectively inhibits heat transfer away from the bag (so essentially a barrier of some type); 4) combine your sleeping bag with the proper sleeping pad to avoid heat loss to the ground; 5) the formulas may or may not tell the full story, but may provide a starting point/guide when initially evaluating sleeping bags; 6) you might be able to use an additional/supplemental outer bag/cover/whatever to increase the efficiency of your bag/sleeping system; and 7) ask a lot of questions at the store, people using the bags, etc.. Understanding the different ratings, how they are used, and what they mean is very helpful. Another important thing to remember (for me) is not to be so focused on one brand or another, that you miss a really great product(s) from another (rival?) company. Thanks again for the information.

[iamdorusyt]

Interesting video! I never heard about this equation before, this will probably come in handy when looking for my next sleeping bag.
Also many thanks for adding metric measurements in the video, makes it much easier to follow for us euro guys.
I wished more US reviewers did.

[jansveen]

This is correct. A lot of the sleeping bags are not living up to the temps they acclaim This is not a big deal if it is summer camping. But for minus temps, this is critical. I have been doing outdoors for most of my life, and tried out a lot of equipment. Stay away from the cheap, that is just not worth the irritation. Still, there are north face, it is just bad, with all their products. They are just a fashion brand.,

[AlbertVicol]

Interesting! SO I did some measurements on my two nemo sleeping bags with same rating. here are my findings:
Nemo Forte with primaloft synthetic rated 20degree F : came at 6.5 cm to even 7cm.
Nemo Tempo synthetic (budget version, 50 bucks difference) came at 3.5 at the very best and feels less loftier and much skinnier. Granted, the tempo was used and forte is new, tempo been compressed couple of times, but no more then 48 hours at max.
It is interesting as I tried 0 to -2 Celsius here in Norway and with tempo in the morning I was feeling chill (night time was fine cause of bottle of hot water). You really make me go out now with my new sleep bag and test it, I am 100% sure it will be much better. Love the video and these type of technical videos is what make me happy!

[louspeed]

Thanks for all the work you put into the video. I am a woman and have a 30-deg REI Magma quilt that has 2.5" of loft. Last year, I was in temps in the low to mid 30s and survived while using a 3.5 R-value pad with blue foam below it. I also had a rechargeable warmer pressed to my chest and a synthetic puffy under the quilt. Not a great night of sleep! This year, I upgraded to an EE 10-deg quilt which has 4" loft and bought a pad with 4.2 R-value so I'm hoping for a much better experience.

[solsang]

That loft measurement would only make sense if the filling was the exactly same type, there are huge differences in down quality and fibre quality, so this really is only an wild guesstimate, also the zipper and neckstrap are important areas of heattrapping

[jjansen]

I have found to put a fleece blanket under my sleeping bag. I have used my 20 degree bag in 10 degree weather this way. Yes this is a pain if your back packing. Great info for my next bag.