Curtain Fabric Calculator
Curtains eat more fabric than people expect, because fullness multiplies the width and hems add to every drop. Enter your window, fullness, and allowances to get the widths per panel, cut length, and total yardage — repeat included.
About 2× is standard; sheers often 2.5–3×, heavy or flat styles 1.5×.
Set repeat to 0 for a plain fabric.
Formula & how it works
Flat width needed is track width × fullness. Per panel that is flat ÷ panels + side hems × 2, and widths per panel is that divided by the usable fabric width, rounded up.
Cut length is finished length + header + bottom hem, rounded up to a whole pattern repeat when one is set. Total fabric is drops × cut length ÷ 36 yards.
Worked example
A 60 inch track at 2× fullness needs 120 inches of flat width, so each of two panels is 60 inches plus 3 inches of side hems — 63 inches, which takes two widths of 54 inch fabric. With an 84 inch finished length plus 8 inch header and 8 inch hem, each drop is 100 inches; four drops is about 11.1 yards. Add a 24 inch repeat and each drop rounds to 120 inches, pushing it to 13.3 yards.
Getting curtains right
Fullness is the biggest lever
Doubling the track width is what gives curtains their gathered fall, and it is also what makes the yardage climb. Dropping from 2.5× to 2× can remove an entire fabric width per panel, so it is worth deciding the look you want before buying rather than after.
Repeats are expensive
Patterned fabric has to be cut so every drop starts at the same point, which means rounding each cut length up to a whole repeat. A large repeat on a long curtain can add a foot or more per drop, and across four drops that is several extra yards.
Measure the track, not the glass
Curtains hang from the track or pole, which usually extends well past the window on both sides so the curtains can stack clear of the glass. Measuring the window itself is the most common reason finished curtains turn out too narrow to close properly.