Understanding the Black Magic behind Sleeping Bag Temperature Ratings - ITS Tactical

Shop the ITS Store!


Understanding the Black Magic behind Sleeping Bag Temperature Ratings

By Buck Holly

Sleeping Bags

Editor-in-Chief’s Note: Buck is back with a few thoughts on the mystery behind sleeping bag temperature ratings. If you’ve ever wondered what those ratings mean, Buck will help to shed some light on the subject. Before you buy your next sleeping bag, be sure to watch this short and informative video.

Buck Holly served 9 years in the Marine Corps Intel Community and is currently the Science & Technology / Force Modernization liaison between DoD Program Staff, Operational Units, Force Modernization Officers, S&T Staff and Defense Industry BD & Engineering.

Are you getting more than 14¢ of value per day from ITS?

Thanks to the generosity of our supporting members, we’ve eliminated annoying ads and obtrusive content. We want your experience here at ITS to be beneficial and enjoyable.

At ITS, our goal is to provide different methods, ideas and knowledge that could one day save your life. If you’re interested in supporting our mission and joining our growing community of supporters, click below to learn more.


  • The Panda

    maybe you shouldn’t have other people talking in the background when making an informative video. amateur hour big time.

  • RayAke

    good read

  • Cameron Melvin

    Just a quick comment.  It totally depends on who did the temperature rating.  If your bag has an EN rating, then it has been “tested” against a specific standard.  It will have a comfort rating, a lower limit rating, and an extreme rating.  Is it perfect no, but at least there is a specific testing protocol against which you can compare not only different sleeping bags, but how you sleep as an individual.

  • ColinElliott

    I have a silk liner that really adds a lot when it starts getting cold.  It’s super light weight and easier to wash than the whole bag.

  • corsair

    That was an amazingly uninformed and poorly explained video.

    There already is an existing standard for measuring sleeping bag warmth: EN (European Norm) Test Method.  Major outdoor retailers (REI, EMS, MEC…) already require that their sleeping bag assortments meet such or, they will not buy/sell them.

    EN testing came about because manufacturers were fudging their temperature ratings (in the quest for lower overall weights) so, the EU mandated that all sleeping bags sold in Europe, needed to be tested by an independent lab.  There are many test methodologies, what was selected, was the easiest for people to understand and explain without having to discuss margin of errors and test irregularities that other tests were saddled with.  Not perfect but, easy enough and accurate enough for the layman to understand.  American manufactures doing business in Europe made a cost effective decision to keep the same for domestic sold products and major retailers were encouraged.


    What the link doesn’t explain is the sleeping bag with the thermal dummy inside is laying on a 1″thick foam mattress and the body is clothed in top/bottom base layer with beanie on head.  The important thing to understand about the EN test is it provides a TEMPERATURE RANGE.  Because everybody’s body functions at a different metabolic rate, the range provides a avg guesstimate of comfort. Other factors will contribute to the effectiveness or, ineffectiveness of a sleeping bag: too thin a mattress pad (NeoAir), exhaustion, exposure to wind/rain, no hot meal, alcohol, medication (legal/illegal), body mass, fat content, dehydration, too big/small sleeping bag, poor circulation, age, etc…

    Buck would’ve done better by explaining the EN test method, the importance of a sleeping pad, pros/cons of various sleeping bag shapes, and why gender specific bags exist.

  • Eugene Grant

    Michał Gałuszek

  • HTEngineer

    @ITSTactical Some of the suggestions aren’t bad, but it isn’t all true, nor is it that factual. More like field mitigation for lack of understanding of the standards. I like ITS, and have been a CL for awhile, and I really don’t want this kind of article to degrade the reputation of this awesome site or lead anyone astray. The key is to buy from the best manufacturers.

    There are multiple testing standards, and the reasoning behind what the company gives you (there are actually THREE temperature ratings under EN, not all report them) will give you a better idea of what they are and what they mean. I don’t know what you want to do about the video/article for the moment. I’m starting a thread under the CL Forum as there could be some conflict of interest stuff at the movement as I work in the industry and that’s a more private place to put things. Maybe we can get this updated and back up.

    • HTEngineer

      Forgot to include this: http://www.rei.com/learn/expert-advice/sleeping-bag-backpacking.html

  • panhandle rancher

    There’s a reason military bags are multi-layered and heavy. They stand up to hard use and can be used with fewer layers when warmer. I have some of the best low temperature expedition bags. Have to treat with care because the external cover is thin and relatively fragile and look likely to burst into flame when heated. Being down filled, such bags cannot be compressed long term without compromising performance. 

    My all season US military performance bags are just that, honest, rugged bags that will function for long periods of hard use. 

    Silk liners are indeed wonderful per one comment. I like silk long johns for cold wear even better. The silk reduces friction between skin and heavy outer garments and still works great in the bag. 

    My thoughts, 

  • Onground Likesleep

    This question came up every time I sold a bag as an outfitter. Buy a rectangular bag at 25 degrees, buy a mummy bag at 25 degrees. Slip one inside the other when it’s reasonable. Use one as the mattress when it’s too warm. Double when cold. Since your body is your heat source, sleep naked or in silk underwear.  Eat a few ounces of cheese 20 minutes before climbing into the bag. Increased metabolism creates more warmth. Cozy.

  • As this was just reposted as part of “Summer’s almost here” article roundup I’d like to second what has been said already that this video needs to be updated with accurate information. Buck’s opinion scale (no offense Buck) is just his experience based off his comfort level. 
    Everyone and every situation is different. My wife and I can sleep in the exact same bed in the exact same house and have extremely different “comfort” ratings when it comes to temperature (she sleeps cold as ice and I’m like a furnace).  That being said the “Black magic” as others have pointed out is there is a standard and it allows you to compare sleeping bags across manufactures.
    There is a lot of technology out there and seems to be a push from the industry to help consumers better understand and equip themselves. A lot of sleeping pads now come with an R Rating (just like the insulation in your attic). 

    I’ve slept in a sleeping bag in various situations around the world from patagonia to Kilimanjaro and It’s best to have a sleep system that is versatile and now how to keep yourself warm and comfortable. 

    There are a lot of experts out there (http://www.outdoorgearlab.com/)  that have done far more research on outdoor sleeping please do some more research and update the video.

    Love what y’all do, keep up the good work.

Do you have what you need to prevail?

Shop the ITS Store for exclusive merchandise, equipment and hard to find tactical gear.

Do you have what you need to prevail? Tap the button below to see what you’re missing.