Quick question on temp ratings

[XSrcing]

I see temp rating thrown around more than burnt popcorn at a b-movie, my question is; how do they come up with this rating?

Will it keep an Arizonian alive at this temp or do you need to be a Shug wearing a onesie made of down filled fleece?

I said it was 55*, but last Saturday night it got down to 48*f and I stayed plenty warm wearing a couple layers, on a foam pad with a fleece blanket.

I'm aware that 48* is no where near 20*, and that this is also very subjective, but i'd just like some feedback before I bust out the thread injector and build some quilts with 5 inches of loft.

[BillyBob58]

Actual temp performance varies quite widely among individuals. Plus even among individuals, results can vary for that same individual on any given day depending on many variables. IOW, you might be toasty in a given quilt on Monday but have a hard time keeping warm on Tuesday. If on Tuesday you are debilitated after a long hike in blowing rain/snow, going to bed already cold, hungry, if the wind is not well blocked, if the insulation is even slightly damp, etc., etc.

So temp ratings by quality companies are usually just based some past testing that has been done to determine that a layer of a given type of insulation at a given thickness will keep the "average" person adequately warm at a given temp. When all is perfect, some will be warm at colder temps, some will not be warm anywhere near those temps. So whether you are average is something you have to determine for yourself. When most of your friends are complaining of cold, are you plenty warm enough? Or is it vice versa? Or are you cold when most other folks near you are also cold?

But even if you are average or even a warm sleeper, the above variables can throw every assumption out the window.

Having said that, I have slept in a JRB MW4 UQ at 10F plus a TQ ( not in a synthetic sleeping bag which would have added some more back warmth) and my back was plenty warm. It is rated, I think, at zero to +5. I am pretty sure I could have gone a bit lower.

I have also slept warm enough ( back warmth) at 10F in a 20F rated Speer PeaPod, only adding a space blanket.

I have slept warm enough at 30F in an HH Super Shelter, which I believe is right about the temp Tom H. said it was good to for him. By adding a down vest under my back and a fleece jacket from about kidney/butt to thighs, I have been toasty at 14 plus huge wind chill, no tarp.

IOW, with the well respected manufacturers, their ratings usually prove about right for me, maybe even a bit conservative. But, in all of these tests, none of the above variables, except maybe wind, was ever a factor. If they had been, I might not have been warm even at warmer temps. But another person might have either been cold in the same test, or been able to go a lot colder. For example, search for posts/threads by or about Cryofthewild, who has regularly taken the basic HHSS- good for me no lower than 30F - to well below zero. So there is a range of about 40 or 50F for you!

[djminnesota]

I have one three season sleepping bag rated around 40*. Ive used it during single digit nights. Alls ya gotta do is wear warmer clothes in the bag

[MedicineMan]

Stated maker/manufacturers temp ratings have no meaning to me except that whatever they state I take 10F off of it. For example they rate their top quilt to 30F then I consider it a 40F quilt for me. That said you will rarely if ever hear me complain about being too hot.

[DivaB]

It goes to personal experience. I sleep hotter than blazes at home, but colder than heck out in the woods ...who would've thought? I'm like MedicineMan and also add about 10 degrees to what I'm doing.

[DemostiX]

All the makers follow the same estimated relation between inches of correctly baffled and filled loft of quality down that you find from the serious domestic makers, like Western Mountaineering. Instead of finding Mike's estimated regression formula, I urge you to study the temp ratings and loft for the line of WM sleeping bags. Of course they show loft for top and bottom layers combined.

There's more complaints here by unpleasantly chilled folks from ill-fitting UQs than from anything else. The reasons for these wardrobe malfunctions are in other threads.

For top quilts and serious cold, I'm sure the drape and seal account for a lot. And cheaper than down for falling and staying asleep all last winter was a draft-stopping dome-protecting fleece balaclava.

[bear bag hanger]

Temp ratings are usually based on the thickness of the sleeping bag or quilt and the type of insulation - usually down or some sort of synthetic material. 2.5 in of down should result in a rating of about 25 to 30 degrees. Don't remember all the formulas, but if someone tells you they have a down bag with one inch of down and is rated down to 25 degrees, you probably want to look elsewhere. Look for consistency in their ratings. Also, remember that a zero degree bag will be very uncomfortable in 50 degree weather, but the reason for that is for another post.

[MAD777]

Western Mountaineering regression equation:

Loft = (67 - Temp) / 18

or

Temp = (18 * Loft) + 67

Temperature is Fahrenheit
Loft is inches

[Flatliner]

'

Western Mountaineering regression equation:

Loft = (67 - Temp) / 18

or

Temp = (18 * Loft) + 67

Temperature is Fahrenheit
Loft is inches

I apologize for reviving an old thread but this is what I was searching for. One question though. Does this apply regardless of material? I am thinking I want to do my first quilt in a synthetic but will likely experiment in the future.

[MAD777]

The formula should work for any fiberous insulation (not CCF pads). The differences among individual metabolism and what they ate for dinner would have more effect than small variations in formulas.