For a pair of simple curtains, calculate how many fabric widths you need, then multiply that number by the length of each cut. Divide inches by 36 to get yards. An 88-inch finished panel in our example needs a 100-inch cut even before a printed pattern changes the calculation.
Here is an example from the Weftward Supply cutting desk: a 96-inch rod, two unlined panels, and a finished length of 88 inches. The prepared fabric is 54 inches wide before removing the selvages. Keep inches on the page until the last calculation.
Decide what you are making before measuring
This example uses rectangular panels attached with clip rings. The fabric runs vertically down each panel, and the pair opens in the middle. Pinch pleats need their own heading calculations. Roman shades and curtains cut sideways across wide fabric also need a different plan. A fixed-pleat heading tape may specify a fullness ratio that replaces the one used here.
Fit the rod and rings before measuring the length. Our 88 inches runs from the bottom of the clip, where the fabric will begin, to the chosen hem position. Measuring from the top of the rod would put some of the hardware's length into the curtain. Sketch the ring above the cloth if that helps you keep the starting point straight.
Measure the drop at both ends of the rod and at the center. An uneven floor can turn one tidy measurement into a curtain that drags at one end. Decide the hem position using those readings. Record the finished length, not a number you have already increased for hems.
Measure the space the closed curtains must cover
Use the working length of the rod, excluding its decorative end pieces. The example rod spans 96 inches. Each panel covers half of that span, or 48 inches, when drawn across the window. If your curtain needs a return toward the wall, include that extra coverage before calculating the fabric width.
Fullness describes the extra width that becomes folds. At two times fullness, a panel covering 48 inches needs 96 inches of finished, flat fabric. Pull it across the rod and the extra cloth gathers. Two times is a choice for this project, not a rule for every fabric or heading.
Before choosing your multiplier, hang a sample of the cloth from the actual clips. Thick material takes up more space when gathered than a thin plain weave. The sample will not tell you the final yardage; it helps you decide whether you want the folds you are about to pay to make.
For our pair, the target is 96 inches of finished flat width per panel. Write that beside the 88-inch finished length. Do not multiply 96 by 88 to order cloth: the bolt comes in a fixed width, and the panels must be cut to fit that width.
Count fabric widths, allowing for the seams
Start with the width you can sew after preparing the fabric and removing its selvages. On our cutting sheet, removing a one-inch selvage from each side leaves 52 usable inches. Measure your cloth or ask the supplier for its usable width. A stiff or printed selvage belongs outside the measurement if you plan to remove it.
Each panel has two side hems, and each hem uses two inches of cloth: a one-inch fold turned twice. One 52-inch width therefore makes a panel only 48 inches wide after hemming. That covers half the rod flat, but it cannot provide the two times fullness we chose.
Join two widths for each panel. A half-inch seam allowance on each joined edge consumes one inch in total. Two widths give 104 inches; the join leaves 103. Subtract four inches for the two side hems, and the finished panel is 99 inches wide.
That is three inches wider than our 96-inch target. In this plan, trim the assembled panel to 100 inches before turning the side hems. Four inches goes into those hems, leaving the intended 96. For two matching panels, we need four full lengths cut from the bolt. Those lengths are often called drops.
Draw four tall rectangles and group them into pairs. Mark the join inside each pair, then mark the side hems on the outside edges. Label one pair LEFT and the other RIGHT. The sketch should show two joins altogether, with four outer side hems.
Add the cloth hidden inside the top and bottom hems
The finished length is 88 inches. For this sample, the top folds down two inches twice, using four inches. The bottom folds up four inches twice, using eight inches. Add 12 inches to the finished length. Each plain-fabric drop must be 100 inches long.
Your own hem allowances may differ. If a pattern specifies a different top finish, use that instruction instead of our four inches. A rod pocket, for example, needs enough cloth for the rod and its construction. Record the allowance as fabric consumed, not the height of the finished fold.
Now multiply four drops by 100 inches: 400 inches. Divide by 36: 11.11 yards, rounded to two decimals. If the supplier sells quarter yards, 11.25 yards is the next available cut above that figure. This is a cutting total for prepared plain fabric. It does not yet include shrinkage or a reserve for straightening uneven ends.
Change the cut length when the print must match
A pattern repeat is the distance until the same part of a design appears again. Suppose the prepared fabric has a straight vertical repeat of 18 inches, measured after any required washing. We want each drop to start at the same point in that design, so the print can line up across the joined widths.
Our plain cut length is 100 inches. Five repeats give only 90 inches, which is too short. Six give 108 inches. Use 108 as the patterned cut length for each of the four drops, making 432 inches. Cutting each drop at 108 inches lets the next one begin at the same point in the repeat.
Allow an additional repeat to find the starting point on the first drop. In this example, that takes the total to 450 inches, or 12.5 yards, before any separate preparation allowance. A large flower might need deliberate placement above the hem; sketch that position before accepting the total.
Matching across joins can consume extra width. Pin two widths together at the proposed seam, align the design, then measure the assembled panel. If it is under 100 inches before side hems, it cannot provide our 96-inch finished width. Recalculate before ordering.
This repeat calculation assumes a straight match. In a half-drop design, adjacent widths match at an offset, so identical starting points may not line up. Ask the supplier, “Is this a straight match or a half-drop match?” Request an image showing adjacent widths. A six-inch swatch cannot show an entire 18-inch repeat.
Account for preparation before placing the order
Read the care instructions for the actual fabric. If the curtains will be washed, decide how you will prepare the cloth before cutting. Do not apply a guessed shrinkage percentage to every fiber. Follow a cotton print's washing instructions if it is washable; do not wash a cloth labeled for dry cleaning to run this experiment.
For a washable fabric, mark a measured sample and prepare it as instructed. Measure between the same marks afterward. A sample changing from 20 inches to 19.5 inches in length has retained 97.5 percent of its length. Your cutting plan needs to use the dimensions the cloth will have after preparation.
If a measured sample supports that 97.5 percent figure, divide your required prepared length by 0.975. Multiplying by 1.025 gives a slightly different result. The original length must be large enough that 97.5 percent of it still supplies your cutting plan. If you add eight inches for straightening, include those eight in the prepared length before dividing.
For our plain example, suppose we choose an eight-inch reserve for straightening the two ends. We need 408 prepared inches. Divide by 0.975 to get 418.46 raw inches, then divide by 36: 11.62 yards. Buying in quarter yards rounds that order up to 11.75 yards. These figures describe the sample calculation, not a predicted shrinkage rate for your fabric.
Keep a worksheet you can check at the cutting desk
Use these entries for the sample plain pair, then replace each figure with your own:
- Rod coverage: 96 inches total, split between two panels.
- Target finished size: 96 inches flat width by 88 inches long per panel.
- Usable cloth: 52 inches wide after preparation and selvage removal.
- Construction: two joined widths per panel; four drops altogether.
- Cut length: 88 inches plus four at the top and eight at the bottom.
- Prepared cutting total: four times 100 inches, or 400 inches.
- Sample order: 11.75 yards after the stated reserve, measured shrinkage, and rounding.
For patterned cloth, replace the plain drop length with the repeat-adjusted length, then show the initial matching allowance on its own line. Confirm the usable width after preparation as well. Width shrinkage can change the number of drops; extra length alone will not rescue a panel that has become too narrow.
Keep lining on a separate sheet. Its width and hem construction may differ from the face fabric, and it does not inherit an 18-inch floral repeat simply because it sits behind a printed curtain. Use the lining method you intend to sew rather than doubling the face-fabric order.
Keep the plain and patterned totals on separate lines of the worksheet. The 11.25-yard cutting total for prepared plain cloth cannot be carried over to the floral version. The window has stayed the same size, but matching the print has changed what you can cut from each yard.
If you plan to split a spare width between panels, draw the split and the added joins. A three-width pair can work for some narrower rods. It will not supply our 192-inch target from 52-inch usable cloth: even three unsewn widths total only 156 inches. Do that width check before trying to save a drop.
Before the first cut
Unroll enough cloth to check the direction of the design. Mark the top of each drop on its wrong side. A print that looks directionless in a thumbnail can have leaves pointing one way across a full panel. Cut all four drops with the same orientation unless the design and cloth allow otherwise.
Lay the first pair beside each other before cutting the remaining drops. Check that the proposed join keeps the pattern where you intended it. Keep the sketch beside the bolt and mark each drop as you cut it: left outer, left inner, right inner, right outer.