To properly measure for drapes, you must determine the width and the length of the window. Once those dimensions are known, you should determine how the drapes should hang. This information is used to determine the proper width and length of drapery needed.
When measuring for drapes, the width is always listed first, then the length. To measure for width, measure the window at the top, middle and bottom. The largest number is the required width for the drapes. Drape fullness is also a factor. Finished drapes should be 1.5 to three times the measured width of the window. For example, a 50-inch-wide window needs 75 to 150 inches of drapery to cover the window. For a tailored look, use the lower number. For a more grand appearance, use the higher number.
To measure the proper length for drapes, measure from the hanging rod down to the desired length of the drapes. Drapes generally hang to the bottom of the window, midway between the bottom of the window and the floor, or to the floor. Do not include the portion of the drapes that hang above the hanging rod. Common lengths for drapes are 84 inches, 95 inches, 108 inches and 120 inches.