Curtain Fabric Calculator

Work out how much fabric curtains need from the window width, the fullness ratio, the drop and the pattern repeat.

Curtain fabric is bought by the drop, not by the window size, and the fullness ratio is what decides how many drops you need. This calculator works from the track or pole width, the finished drop, and the fullness you want, then adds the header and hem allowances and the pattern repeat matching that a print curtain needs.

At a glance

What you enter: Track or pole width, Finished drop, Fullness ratio, Fabric width, Header allowance, Hem allowance, Vertical pattern repeat, Add lining, The window needs a pair of curtains
What you get: Total drops to cut, Cut drop with the repeat matched, Total face fabric length, Face fabric, Face fabric in metres, Lining fabric
Formula shown: Yes, every step, right below your results.
Cost and privacy: Free, no account needed, and nothing you type is stored.

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Track or pole width in

Measure the track or the pole, not the window. Add the return to the wall if the curtains wrap around.

Finished drop in

From the bottom of the track or the eye of the ring to the finished bottom edge. Subtract 0.5 in for floor clearance if you want them just off the floor.

Fullness ratio

The header tape states the fullness it is designed for. Less fullness than the tape asks for gives flat, mean looking pleats.

Fabric width in

Curtain fabric is usually 54 in or 60 in. A narrow 44 in fabric needs more drops.

Header allowance in

About 8 in for pencil pleat tape, 10 to 12 in for a deep pinch pleat or a goblet heading.

Hem allowance in

8 in gives a double 4 in hem, which hangs better. 4 in is the minimum.

Vertical pattern repeat in

Measure between two identical points in the print. Leave at zero for a plain fabric.

Add lining

Lining is cut to the same drops and widths. Interlining goes in the same calculation.

The window needs a pair of curtains

Most windows are dressed with two curtains that meet in the middle. The total fabric is the same either way; this only changes the drops per side.

Reset

Results are estimates for general information only, always verify with a professional or official source before acting on them.

How to use the Curtain Fabric Calculator

1 Enter Track or pole width (in), Measure the track or the pole, not the window. Add the return to the wall if the curtains wrap around.
2 Enter Finished drop (in), From the bottom of the track or the eye of the ring to the finished bottom edge. Subtract 0.5 in for floor clearance if you want them just off the floor.
3 Enter Fullness ratio, The header tape states the fullness it is designed for. Less fullness than the tape asks for gives flat, mean looking pleats.
4 Enter Fabric width (in), Curtain fabric is usually 54 in or 60 in. A narrow 44 in fabric needs more drops.
5 Enter Header allowance (in), About 8 in for pencil pleat tape, 10 to 12 in for a deep pinch pleat or a goblet heading.
6 Enter Hem allowance (in), 8 in gives a double 4 in hem, which hangs better. 4 in is the minimum.
7 Enter Vertical pattern repeat (in), Measure between two identical points in the print. Leave at zero for a plain fabric.
8 Enter Add lining, Lining is cut to the same drops and widths. Interlining goes in the same calculation.
9 Enter The window needs a pair of curtains, Most windows are dressed with two curtains that meet in the middle. The total fabric is the same either way; this only changes the drops per side.
10 Press Calculate. You get Total drops to cut, Cut drop with the repeat matched, Total face fabric length, Face fabric, Face fabric in metres, Lining fabric, and every intermediate step stays visible under "How is this calculated?"
11 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.

Worked examples

Real numbers run through this calculator. Open any example to load it into the form above and change it.

Pencil pleat curtains for a 72 inch window

A 72 inch track at 2 times fullness, a 90 inch drop, 54 inch fabric, no pattern repeat.

You enter

Track or pole width: 72 in
Finished drop: 90 in
Fullness ratio: 2
Fabric width: 54 in
Header allowance: 8 in
Hem allowance: 8 in
Vertical pattern repeat: 0 in
Add lining: No
The window needs a pair of curtains: Yes

You get

Total drops to cut: 4
Cut drop with the repeat matched: 106.00 in
Total face fabric length: 424.00 in
Face fabric: 11.78 yd
Face fabric in metres: 10.77 m
Lining fabric: 0.00 yd

Four drops in total means two drops per side, which is the usual arrangement for a window of this width.

Open this example in the calculator →

Pinch pleat curtains with a large repeat

A 100 inch track at 2.5 times fullness, a 96 inch drop, 54 inch fabric and a 24 inch pattern repeat, with lining.

You enter

Track or pole width: 100 in
Finished drop: 96 in
Fullness ratio: 3
Fabric width: 54 in
Header allowance: 10 in
Hem allowance: 8 in
Vertical pattern repeat: 24 in
Add lining: Yes
The window needs a pair of curtains: Yes

You get

Total drops to cut: 6
Cut drop with the repeat matched: 120.00 in
Total face fabric length: 720.00 in
Face fabric: 20.00 yd
Face fabric in metres: 18.29 m
Lining fabric: 20.00 yd

Matching the repeat rounds every drop up to a whole repeat, which across ten drops adds several yards to the order.

Open this example in the calculator →

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Frequently asked questions

What fullness should curtains be?

Pencil pleat and pinch pleat headings are normally gathered to 2 to 2.5 times the track width, and eyelet curtains on a pole to 1.5 to 2 times. A flat panel or a cafe curtain is 1 to 1.5 times. The header tape states the fullness it is designed for, and using less than that produces pleats that lie flat and look mean.

How do I calculate curtain fabric with a pattern repeat?

Add the repeat to each drop, not to the total. Every drop has to be cut starting at the same point in the design so the seams match, so you lose the part repeat at the end of each length. A 24 inch repeat on a 90 inch cut drop can push each drop to 96 inches, which on six drops is a whole extra yard of fabric.

Should I measure the window or the track?

The track or the pole, every time. Curtains are made to the track width, and the window opening is only relevant if you want the curtains to stack clear of the glass when open. For a pole, add the return distance to the wall at each end. Allow the stack back, which is roughly a quarter of the flat width for a pencil pleat.

How much fabric do curtains need for a 72 inch window?

At 2.5 times fullness, a 72 inch track needs 180 inches of flat width, which is four 54 inch drops once you round up to whole widths. A 90 inch drop with an 8 inch header and an 8 inch hem gives a 106 inch cut drop per length, so roughly 12 yards of face fabric. A pair of curtains needs the same total fabric, arranged as two drops each side.

Do I need to add extra for the hem and header?

Yes, and it is the allowance people most often forget. A pencil pleat heading takes about 8 inches turned back, and a deep pinch pleat up to 12. A double 4 inch hem takes 8 inches. On a 90 inch drop that is nearly 16 inches of fabric per length that never appears in the finished curtain, which across four drops is close to 2 yards.

Terms used here

Short, plain-language definitions of the words this calculator uses.

Fullness ratio How much wider the fabric for a curtain is than the window or track it covers. Grainline The direction of the threads in a woven fabric. Pattern repeat The distance before a printed or woven design repeats along a length of fabric.

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