How much down fill to use

[Rmaisonville3]

Hello,

Looking to make a 40 degree 3/4 underquilt. How much down would you recommend use for this?
Thanks

[fuzzypiper]

It depends on the dimensions of your quilt. You need to calculate the cubic inches for each channel and divide by the power fill you'll use. For example, if each channel is 4"x50"x 1.5" (loft), your cubic inches is 300". Divide that by your power fill, say 800, and your ounces per channel is .375oz.

There's an underquilt spreadsheet someone made. Here's the link: https://www.hammockforums.net/forum/...ilt+calculator

As for loft for 40 degrees, most vendors believe 1.5" of loft is about 40. Here's hammock gear's specs: https://www.hammockgear.com/content/...um_Phoenix.pdf

[Trambo]

In addition to that spreadsheet, here are some more references
UQ Chart Matrix - https://docs.google.com/spreadsheets...it?usp=sharing
Sleeping Pad R values - https://sectionhiker.com/sleeping-pad-r-values/

I'm planning on making a karo style UQ with 6 ounces of down, so that I keep the ability to add more down and make it into a winter UQ.

[wvumountaineer52]

Baffles loft heights are .5 inch per 10’degrees it looks like based on gear company charts....1.5=40. 2=30. 2.5=20 so on. I used this formula to measure the amount down I’ll need in my quilts...

Length x Width x Loft / Fill Power x 1.1 =

Example:
75x55x2 = _____ / 800 = 22.10 oz (24 oz)


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[wvumountaineer52]

Whoops hit share too early...

Length x Width x Loft / Fill Power x 1.1 =

Example

75x55x2=8,250/ 800 = 10.31 oz x 1.1 = 11.31 oz


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