Draw a quick sketch of the entire wall including the windows to be covered. Use a metal tape measure. Measure the height and width of the wall. Measure the window length and width; include all of the top moldings and the window sill. Add the measurements from the top of the window frame to the ceiling and the window sill to the floor. Measure each window for window coverings separately.
Calculate the length of the draperies. Add at least 18 inches for headers at the top and hems on the bottom for a total length measurement. Figure pleated draperies at a triple fullness of three to one. An example of this calculation is that a 48-inch wide strip of fabric will pleat to a width of 16 inches at triple fullness. Divide 48 by three to get 16 inches. Join these widths together to form panels of draperies. Use this calculation for any fabric, lined or unlined, and for any length.
Draperies gathered on poles, with or without rings, are calculated at double fullness. Calculate for a gathered drapery that is less full at two to one. A double-fullness finished width using 48 inch wide fabric is 24 inches.
Cover all side moldings on the window frames, and draperies should be floor length or longer to hang properly. Add an overlap on each side if the draperies are to open and close properly on a traverse rod. Five inches added to each side allows the draperies to overlap slightly to cover the middle. Draperies on a rod with a return to the wall will need an additional 4 or 5 inches added to each side to cover that return and make the draperies cover the entire rod to the wall. Wooden poles or fixed panel draperies do not require any additional panels for the overlap or the return.
Calculate the stack back. The amount of space the drapery will take on the wall when fully open is called the stack back. A window opening of 62 inches with a triple fullness drapery will stack back to 34 inches. Hang the rod wider than the window opening to allow the glass to show. The stack-back calculations mean that with triple fullness, the drapery will take about half of its own total width when it is open.
Use this example when calculating: Fabric requirements for triple-fullness gathered curtains on an 8 foot high wall, with a window size of 62 inches wide and 48 inches high: width of 62 inches, plus stack back of 34 inches, plus overlap of 8 inches, plus returns of 8 inches, and this equals 112 inches. Use 48-inch fabric which gathers to 16 inches wide. This means that you need seven widths for this window. Calculate lengths with a ceiling height of 96 inches, plus 18 inches for hems and headers, and this equals 114 inches for each length. Multiply 114 inches by seven widths required for a total of 798 inches or 22 yards, 6 inches.
Things You Will Need
- Metal tape measure
- Pencil and paper
- Fabric with a pattern repeat will require additional yardage.