Before measuring windows, select the style of curtain, drapery or shade you will make. The style of window treatment determines what installation hardware is necessary. Next, decide exactly where the window treatment will be placed; install the hardware and measure this area for the finished size of the curtain, shade or drapery.

Curtain rods may be attached to the window frame, within or at the sides of the frame, on the wall above the frame, or at the ceiling. Mounting boards are necessary for hanging Roman shades and other shades based on the Roman shade construction. These 1″x 2″ (2.5 x 5 cm) boards are cut to the width of the shade, stapled or tacked to the shade’s upper edge, then installed at the window. An inside mounted shade fits firmly inside the top of the window frame. An inside mounted shade is installed on the wall above the frame. A hybrid mounted shade is a combination mount. The mounting board is placed inside the window, but the shade extends over part of the window frame.

Roller shades are installed inside or on the window frame, or on the wall above. Follow these guidelines for accurate measuring:

1) Use a folding ruler or metal tape for measuring; cloth tapes may stretch or sag.

2) Measure and record the measurements for all windows separately even if they appear to be the same size. Size differences, even if slight, should be taken into account when constructing window treatments.

3) When measuring for a shade that fits inside the window, measure the window width at the top, center and bottom to determine if it is true and square.

4) When measuring for curtains on a window without an apron, measure to at least 4″ (10 cm) below the sill.

Window Measurements for Curtains, Shades and Draperies

Estimating Yardage Because fabric widths vary, yardage cannot be figured until the fabric has been selected. After you have taken the necessary measurements and determined the finished size of the curtain, shade or drapery, you must add to the length and width for seams, hems, headings and fullness. This is the cut length. Use the cut length to estimate the amount of fabric you will need. For curtains and draperies, use the amounts as listed below and transfer the correct amount to the chart (right). For shade yardage, see individual instructions for each type of shade.

Determining Length To the finished length, add the amount needed for lower hems, casings, headings and pattern repeat. Lower hems. Add double the desired hem to the finished length. For medium weight fabrics, use a 4″ (10 cm) double-fold hem on floor-length curtains or draperies; add 8″ (20.5 cm) to the length. Or on short curtains or valances, use a I” to 3″ (2.5 to 7.5 cm) double-fold hem; add 2″ to 6″ (5 to 15 cm) to the length. For sheer and lightweight fabrics, a deeper double-fold hem of 5″ to 6″ (12.5 to 15 cm) may be used; add 10″ to 12″ (25.5 to 30.5 cm) to the length.

Casings and headings: For simple casings with no heading, add an amount equal to the diameter of the rod plus V2″ (1.3 cm) to turn under and 1/4″ to I” (6 mm to 2.5 cm) ease. The amount of ease depends on the size of the rod and thickness of the fabric. Lightweight fabrics require less ease; casings for large rods require more. For casings with headings, use the formula for a simple casing, adding to it an amount twice the depth of the heading.

Pattern repeat: Fabrics with patterns (motifs) need to be matched. Measure the distance between motifs and add that amount to the length of each panel.

Determining Width To the finished width, add the amount needed for seams, side hems and fullness. Seams. For multi-width panels, add I” (2.5 cm) for each seam. Panels that is not wider than the fabric do not require an extra amount for seams. Side hems. Add 4″ (10 cm) per panel for a I” (2.5 cm) double-fold hem on each side of the panel.

Fullness: Fabric weight determines fullness. For medium to heavyweight fabrics, add two to two and one-half times the finished width of the curtain. For sheer and lightweight fabrics, add two and one-half to three times the finished width.