How to Calculate Fabric in Order to Sew Window Valances

Window valances are a quick way to spruce up any room, but they can be very costly.  Save money and make your own with a few basic sewing supplies and beginning sewing skills.  With some measurements and math, you can figure how much fabric will be needed.

1. Install the rod the window valance will be hanging on.  Measure the length of the window starting at the top of the rod to the top of the lower window casing.  Measure the width of the window starting at the outside edge of each side of the casing.  Write the measurements down.


2. Calculate the base height of the window valance.  To do this, use the measurement length and divide by 3.  Then add 3 inches to the new measurement to allow for the seams and rod casing.  An example, if the window length is 42 inches divide by 3 that equals 14 then add 3 inches that equals 17 inches.  The new height measurement is 17 inches.


3. Figure the base width of your window valance.  To do this, use the width measurement you originally started with.  For a gathered window valance multiply this number by 2 to allow for the gathering.  For a tailored valance, leave the measurement the same.  For example, if your base width is 60 inches multiply by 2 equals 120 inches.  Don't forget to add 2 inches to allow for the seams.  The new measurement would be 122 inches.  For a tailored valance, the new measurement would be 62 inches.


4. Calculate how many valances height measurements you can fit onto the fabric.  To figure, use the width of your fabric and divide by the final height measurement.  For example, the fabric is 44 inches and the height measures 17 inches.  Two full valances can be cut out of that fabric.


5. Divide the final valance length measurement by the number of valance heights you can fit on the fabric.  For example, your final valance length measurement is 122 inches and two valance heights will fit on the fabric.  Divide 122 by 2, this equals 61 inches.  This number is the number of inches of fabric needed for the valance.


6. Convert inches into yards.  To do this, divide the inches measurement by 36.  For example, 61 inches divided by 36 equals 1.69444 yards.  Round your number up to the closest quarter yard.  Therefore, you will need 1.75 yards of fabric for your window valance.