I find a window biography is helpful when you are calculating for the first few times.
We would like the drapery to be 82″w x 104″l.
The fabric is 54″wide
The next step is to determine the number of WIDTHS of fabric that are needed.
72″ + 4″(for overlap in the centre when closed) + 6″ ( 3″ past the frame on teach side) = 82″
82 x 2.5 (for fullness) = 205″
205 / 54″ = 3.79 widths (round up to 4)
Next is the LENGTH of the cuts
108 (the finished length) +12 (for hems & header) = 120
120″l cuts X 4 widths = 480″
480 / 36″(yard) = 12.88(round up to)
There are many different types of pleats and details to choose from.
“Mount your drapery rods as high as you can & use decorative hardware whenever possible”.
These are 2 things that make a huge difference with the finished result.
Mount your drapery rod above the arch to give the illusion of even taller windows.
By doing this, it will actually enhance the architectural detail.