Understanding Sleeping Bag Temp Ratings, Part I and II, By Matt Wymer

Justin Crossley

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How do you know which sleeping bag will work for you? Most of them have temperature ratings so it should be easy right? Yeah, not so much. Matt Wymer learned the hard way like a lot of us do that not all sleeping bags are created equal. This article Understanding Sleeping Bag Temperature Ratings helps to clarify a few things about how companies come up with their ratings and what it might mean to you.

Ready for more? Part II is live!

My Sleep Systems Part II
 
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Paulyester

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Interesting, I always knew manikin to be a "midget", which is what caught my attention in the article lol. I didn't realize it had a secondary definition as well.

Still good article
 

Trial153

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Good read. You’d think it would be incumbent upon the manufacturer to clearly state what exactly the rating they assigned means. Alas that is to much to ask.
 

Ridge Runner

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I've always assumed the temperature rating was a number that guaranteed you would not freeze to death. That's what my experience has taught me, although at times I have wondered if that was true.
 

Matt W.

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I've always assumed the temperature rating was a number that guaranteed you would not freeze to death. That's what my experience has taught me, although at times I have wondered if that was true.

I too think that is most often the case, but its typically not marketed that way.... I like companies that list data out like Exped did.. We should make a list of transparent manufacturers... sure would make it easier to compare info....
 

bobhunts

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I always buy a bag rated for lower temp rating than I think I will need. On my archery hunting trips I won't use a bag rated for over 15 degrees. If I get hot I can unzip my bag. But if I get cold I am covered.
 
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It is surprising that the temperature ratings are so complex when the thickness (or "loft") of the insulation is all that really matters. The thickness of the insulation corresponds directly to how well it insulates. This is a basic principle of thermodynamics.

It's more complicated when you're sleeping on a windy ridge and of course there are differences among people's metabolism that keeps them warmer or cooler at night. It sure would be nice if the manufacturers would simply measure the loft of their material.
 

Matt W.

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I think the key learning for me is that a temperature measuring standard exists, but the rating the industry typically uses does not translate to what works for me. I now go by the comfort rating, which means digging into the specs a bit, but have found that works well for how I sleep.
 

daddywagz

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Great articles on sleep systems, thanks for writing these. Got a couple of questions on bivy sacks. Do you ever feel like they're compressing the loft on your sleeping bag/quilt? Also, are the ones you use big enough so you can sleep on your side in them? I've got a cheapo SOL bivy: it actually saved me one time, and it's super light weight, but I feel like it's not really ideal because it's pretty tight around the bag - not sure on that. I use it with a sil tarp.
 

Matt W.

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Great articles on sleep systems, thanks for writing these. Got a couple of questions on bivy sacks. Do you ever feel like they're compressing the loft on your sleeping bag/quilt? Also, are the ones you use big enough so you can sleep on your side in them? I've got a cheapo SOL bivy: it actually saved me one time, and it's super light weight, but I feel like it's not really ideal because it's pretty tight around the bag - not sure on that. I use it with a sil tarp.
The quilt bivy combo I referenced does not appear to do this as I've got plenty of room in the Bivy / Quilt combo I use. I think it is quite different than the SOL bivy in how it fits. I would not use the SOL bivy as I described above. I to have SOL bivy I sometimes carry, but have always viewed it as an emergency option vs. standard use. Hope that helps!
 

ericthered

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Do you have a go to pillow recommendation for the back country. Just bought the Thermarest NeoAir Xtherm Max on your recommendation for my sheep hunt.
 

Matt W.

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I struggle with finding the perfect pillow myself. I have used a few different ones, but none I'm happy enough with to recommend. A stuff sack and a puffy jacket work in a pinch. ;)
 

WLD

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How do you know which sleeping bag will work for you? Most of them have temperature ratings so it should be easy right? Yeah, not so much. Matt Wymer learned the hard way like a lot of us do that not all sleeping bags are created equal. This article Understanding Sleeping Bag Temperature Ratings helps to clarify a few things about how companies come up with their ratings and what it might mean to you.

Ready for more? Part II is live!
My Sleep Systems Part II
Great article
 
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