Swags and jabots on curtains can really improve the look of a room. It can be difficult, however, to figure the amount of fabric needed for each window. Once the fabric is cut, it is difficult to add or change it, so you need to know the correct amount before you cut or order the fabric. It is not difficult to figure out the amount you need; it does require some simple measuring and math.
Measure the finished width of your window treatment. This is how wide you want it to be when it is completed.
Measure the finished length of the window treatment. This is the measurement from the curtain rod to where you want the fabric to stop. If the curtain goes down to the floor, measure all the way to the floor.
Measure the fabric width of the fabric you are thinking to use. If you have not picked a fabric or do not know the width, figure this with several widths so that you can check it when you pick out fabric. Common widths are 48, 54 and 60 inches.
Divide the finished width by the width of the fabric. For example, if you need 90 inches and have fabric that is 48 inches wide, then your equation would be 90 / 48 = 1.875 yards. To be safe, round the number up to two yards. You will need to sew these two pieces together to achieve the required width, if you want it all in one panel.
Figure the length of fabric you need by adding 12 inches to the length of the window treatment. This will allow enough extra room for hems and seams. Multiply this number by 2, since you will need the curtain to fall on both sides of the window. For example, if you want it to fall four feet, your equation would be 48 + 12 X 2 = 120 inches.
Divide the 120 inches number by 36, which is also one yard. This will tell you how many yards of fabric you will need. Your equation is 120 / 36 = 3.33 yards. You may want to round up to 3.5 yards, just to be sure.
Purchase 3.5 yards of fabric for each window swag, according to these measurements. Your finished piece of fabric for your swag, according to this example, would be 2 yards by 3.5 yards after sewing all the pieces together.
If you think your calculations may be off a little, add a quarter yard of fabric to your initial measurement. It is always better have a little extra fabric than not quite enough.