How to Figure Square Yards for Window Curtains

Determine where to hang the curtain rod. The curtain rod should hang approximately 4 inches above the window frame and extend approximately 3 to 6 inches beyond the width of the window. Measure the diameter of the rod.

Use the position of the curtain rod as a starting point and measure the intended length of the curtains, holding the end of the tape at the top point of the rod. The finished length may be just past the sill, a few inches below the sill or to the floor. Make a note of the final length for your curtains.

Measure the length of the rod, excluding the end supports or finials. Measure only the length of rod from which the curtains will hang. If the rod has returns and the curtains will wrap around the returns, include the length of returns in the measurement. Make a note of this figure.

Add 8 inches to the desired finished length measurement. You need 2 inches to hem the pocket and 6 inches to double hem the bottom of the curtains.

Add the diameter of the rod to the finished length as well plus 1 inch. You need that fabric to create the pocket header of the curtain panels.

Figure the width of fabric needed for the curtain panels. The width of the fabric is determined by the fullness of the finished curtain. Fullness describes the way certain fabrics hang, producing folds and depth of the folds.

Multiply the length of the rod by 2.5 for sheer or lightweight fabrics. Multiply the rod length by 2 for medium weight fabrics. For lace or flat panel curtains, multiply the rod length by 1.5. The resulting figure from your multiplication is the finished width of the curtains across the window.

Add 2 inches to the finished width figure to account for 1/2 inch hems along the length of each side of the curtain panels.

Multiply the final figure of the length of the curtains by the final figure of the width of the curtains. This figure represents how many square inches of fabric is required for the curtains.

Convert the figure into square yards by first converting it to square feet. One square foot equals 144 square inches. Divide the figure by 144. The result is now how many square feet of fabric is required for the curtains.

Divide the resulting figure (square feet) by nine to get the number of square yards of fabric needed for the project. Round up the resulting figure to ensure you have enough to finish.