How much down/loft?

**AsaHanger** · 10-18-2016, 17:33

Ive decided my next diy project is going to be an underquilt for my wife (followed by one for me). Im strongly considering a karo step design. I would like this to be a very warm quilt (0 degree?) as my wife is a cold sleeper.
Ive figured that length*width*height/fill power will give me the number of ounces of down i will need for the quilt. But i dont know how much loft will give me the temp rating im looking at.
Does anyone have any ideas as to how much loft id need?

**IRONFISH45** · 10-18-2016, 18:00

Some place on HF there is a calculator on a spread sheet it will give you everything you need to calculate the supplies you need to build your quilt. I am using my cell phone or I would look the calculator up for you. Poke around a bit and you will find the information you seek. I would guess (strictly a guess) 3.5 inch baffles, you need to find the calculator to be sure. JFYI I cut my own baffles, it is quick and easy, then I have exactly what I need.

**Merganser** · 10-18-2016, 18:27

Here is a link to the calculator thread. There are a couple evolutions, the latest version being on Google Sheets.

https://www.hammockforums.net/forum/...ad.php?t=53701

**AsaHanger** · 10-18-2016, 19:24

Thanks for the replies. That will be a big help in designing this.

**Calait** · 10-18-2016, 23:03

Is there a calculator which allows you to determine temperature of the under-quilt? In central Texas it does get to 30 degrees during the winter however it does not get down to -2 degrees F very often. I may need a 20 degree UQ at most

**GadgetUK437** · 10-19-2016, 01:02

The one linked does that.

Here is the direct link to the post with Boston's modified calculator,
https://www.hammockforums.net/forum/....php?p=1317305

And this is Tacblade's version, with metric conversion,
https://docs.google.com/spreadsheets...LAE/edit#gid=4

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Gadget

**captainhaddock** · 10-19-2016, 05:53

Originally Posted by GadgetUK437

And this is Tacblade's version, with metric conversion,
https://docs.google.com/spreadsheets...LAE/edit#gid=4

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Gadget

Hadn't seen Tacblades version before. Wrote my own metric version based upon the original. This one is much better. Thanks for this! :-)

**Caminante** · 10-19-2016, 08:32

Temperature rating is a function of loft for down. The calculators are great and what I've used on my builds. If you want to understand where the ratings come from, there are charts which show temperature rating as a function of inches of loft. Empirically determined, I suppose, should be adjusted if you are a hot or cold sleeper. Dream Hammock's is very good:

http://www.dream-hammock.com/DownLoftTemp.html

**AsaHanger** · 10-19-2016, 08:48

Originally Posted by Calait

Is there a calculator which allows you to determine temperature of the under-quilt? In central Texas it does get to 30 degrees during the winter however it does not get down to -2 degrees F very often. I may need a 20 degree UQ at most

Here in Utah, 30*F is not uncommon in the mountains in the middle of summer. I've gone camping in mid-August on several different occasions and had the dog's water freeze overnight.

**Rain Man** · 10-19-2016, 11:44

I made two DIY UQs, both modified KARO baffling, and aiming one for 20 degrees and one for 0 degrees. Not sure where I found the guideline, but figured on 2" baffles for 20 degrees and 3" baffles for 0 degrees. That yields about 2.5" of insulation and 3.5" of insulation, assuming enough down to "puff out" the quilts between the baffles. By just looking at the UQs, that appears close to accurate.

I've slept in my backyard at minus-2 degrees (with the 0 degree UQ) and was fine, so think my projects came out fine for me.