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  1. #1

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    Confusion about down fill calculation

    Help.
    I am running into some confusion trying to calculated the total own needed for my underquilt.

    I know the formula is (l x W x h)/fill power * (% over stuff)

    There seems to be no consensus on the "h". I have looked at a lot of threads, quilt instructions and websites. It seems just as many people use loft height as use baffle height. That extra 1/2" (minimum) makes a big difference in the total fill required.

    Which is the correct measurement to use - loft or baffle height?

    Thanks,
    jaso

  2. #2
    Senior Member G.L.P.'s Avatar
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    Quote Originally Posted by jwright View Post
    Help.
    I am running into some confusion trying to calculated the total own needed for my underquilt.

    I know the formula is (l x W x h)/fill power * (% over stuff)

    There seems to be no consensus on the "h". I have looked at a lot of threads, quilt instructions and websites. It seems just as many people use loft height as use baffle height. That extra 1/2" (minimum) makes a big difference in the total fill required.

    Which is the correct measurement to use - loft or baffle height?

    Thanks,
    jaso
    for me it's Baffle height .... Loft is a Byproduct of Down so it will never be a constant too many factors involved like fill power,quality of the down,ex.
    i always use baffle height and never had a problem with any UQ being under filled but i always add 20% overstuff
    all the differential cut is doing is preventing you from squashing your down when you lay in your hammock so it's not like your really adding extra space your compensating for space that will be lost in a way... just my take on it
    there is an old saying there is more then one way to skin a cat ... and i know of a few different ways to calculate fill to airspace in a quilt...in the end they all pretty much work... this is what has worked for me
    It puts the Underquilt on it's hammock ... It does this whenever it gets cold

  3. #3
    Senior Member Grinder's Avatar
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    +1 on the overstuff.

    When I made my UQ last year, I calculated the amount of down by the formula you quoted.

    My channels run from side to side, like the JRB UQ's. There is a tendency for the down to flow away from the outside to the lower middle, leaving cool spots on the elbows.

    I would definitely overstuff 20 % to correct for this.
    grinder

  4. #4

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    Thanks guys.

    I like the idea of using baffle height-- it is an easily measurable constant, while the "loft", like you noted, is somewhat less controlled, likely to vary over the quilt and harder to accurately measure.

    Baffle height it is, with a 20% over stuff.
    Thanks,
    Jason

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