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please check my fabric calculations

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  • please check my fabric calculations

    Hello, will someone please check my calculations for the curtains I'm due to make as I dont think they have bought enough fabric. The shop she bought the fabric from calculated her yardage at 35mts but I have worked it out at 42mts and as there is such a huge difference a large dollop of self doubt is creeping in.

    Curtain track is 150cm
    Finished curtain length before hems and heading is 256cm
    Fabric width is 148cm
    Pattern repeat is 63cm

    I estimated that they would need 14mtrs of fabric for each pair of curtains, four drops for each set of curtains. There is going to be three sets of curtains therefore 42mts of fabric needed, is this correct?

    The person who I am making the curtains for bought 35mtrs of fabric as this is what the shop calculated her yardage as, have I over estimated.

  • #2
    Re: please check my fabric calculations

    What heading and fullness are you using?


    • #3
      Re: please check my fabric calculations

      Hi Marian,
      Using "simple" working out, I estimate that you need a cut drop of 315cms x 4 for each curtain = 12.6 metres for each pair x 3 pairs = 37.8 metres. What heading are you using? I would put 3 drops at each window rather than 4 even for triple pleat, which would reduce the fabric requirement to 28.35. With four drops you're getting nearly 4 x fullness. Maybe I'm just a mean Yorkshirewoman!

      My workings out are based on 256 + 25 = 281cm, divided by 63 = 4.46 = 5 pattern repeats per drop = 315cm. Maybe the shop got it to 35 metres by adding 3 x 315 = 9.45 then adding one drop of 281, making 12.26. (That would be 36.78, which is still more than she has bought.) I know a lot of shops calculate fabric requirement that way, but I prefer my "simple" calculation which gives a bit of leeway for placing pattern etc.
      Hope this helps!


      • #4
        Re: please check my fabric calculations

        4 drops per window seems very full to me.
        For pencil pleat heading it is borderline 1 widths, but not very full. I would allow 1.5 widths and may be cut them down a bit.
        Handsewn headings with 2.5 times fullness would also require a pair of 1.5 widths. So the same fabric quantity for both

        256cm finished drop plus 30cm turnings = 286
        286/63 (pattern repeat) = 4.5
        5 x 63 = 315cm per drop

        315 x 3 = 945cm per pair

        945 x 3 = 2835

        I add 5% for pettern repeat allowance

        29.8m required

        Hope that helps,



        • #5
          Re: please check my fabric calculations

          Even at 3x fullness I only get to 12.6m per pair (4 drops with pattern match included) which makes 3 pairs 37.8m.

          Assuming you are not going over 2.5x fullness then 3 drops per pair should be adequate.

          sigpic Simply Sewing


          • #6
            Re: please check my fabric calculations

            thank you everyone, you've all just confirmed by further workings out, and yes I was over generous with my amount of drops, where I got 4 drops per pair of curtains is beyond me, lets call it a senior moment