How much fabric do I need for curtains?

Multiply your track width by the fullness ratio, divide by your fabric width, and round up — that is the number of fabric widths. Multiply that by the cut length (your drop plus hem allowance) for the total. For example, a 240 cm track at 2× fullness on 137 cm fabric needs 4 widths.

What fullness ratio should I use?

Between 1.5 and 2.5 times the track width is typical. Pencil and pinch pleat headings look best at 2 to 2.5; eyelet headings work around 1.5 to 2. Below 1.5 curtains look flat, and above 2.5 they are very full and heavy.

Do I need extra fabric for a pattern repeat?

Yes. With a patterned fabric, every cut length must round up to a whole pattern repeat so the design lines up across widths, which adds fabric — sometimes a lot with large repeats. This calculator assumes plain fabric, so add the repeat allowance yourself.

Can I calculate in inches as well as centimetres?

Yes. Switch the units selector to inches or centimetres and enter every measurement in that unit. The result is shown in the same unit, with a rough metre or yard total to help you buy fabric off the roll.

How much extra fabric should I buy?

Around 10% more than the calculated total is sensible — it covers pattern matching, shrinkage after washing, and cutting mistakes. The calculator shows this +10% figure for you. Always measure your window twice before ordering.

Curtain Fabric Calculator | Free Online Tool

How to use

1.Pick your units, then enter the track or pole width, the finished curtain drop, your fullness ratio, and the width of your fabric.
2.Set the hem and heading allowance (20–25 cm / 8–10 in is typical) to add to the drop for turnings.
3.Read the results live: how many fabric widths to cut, the cut length per width, and the total fabric to buy (with a +10% margin).

About Curtain Fabric Calculator

To work out how much fabric you need for curtains, multiply your track or pole width by the fullness ratio, divide by the width of your fabric, and round up to the next whole number — that is how many fabric widths (drops) you cut. Then add your hem and heading allowance to the finished drop to get each cut length, and multiply the two together for the total fabric. This calculator does all three steps live as you type.

The first number, the fabric widths, is the one most people get wrong. A curtain has to be gathered to look full, so a 240 cm track at double fullness needs 480 cm of fabric across. If your fabric is 137 cm wide, 480 ÷ 137 is 3.5 — and because you cannot buy half a width, you round up to 4 widths. Rounding up is the whole point: 3 widths would leave the curtain too flat to pleat properly.

The second number is the cut length. Your finished drop is the distance from the hook or track down to where the hem should sit. On top of that you add turnings: a few centimetres folded over at the heading and a deeper double hem at the bottom. A common combined allowance is 20–25 cm, but set your own value to match your heading tape and hem style. Cut length = drop + hem allowance.

The third number is the total: widths × cut length. A 4-width curtain with a 185 cm cut length needs 4 × 185 = 740 cm, or about 7.4 metres. Switch the calculator to inches if you buy fabric by the yard.

Fullness is a matter of look and heading. Pencil pleat and pinch pleat headings usually want 2 to 2.5 times the track width; eyelet headings sit happily around 1.5 to 2. Less than 1.5 tends to look mean; more than 2.5 is generous but heavy.

Two things this calculator keeps simple. It assumes plain fabric with no pattern repeat — if your fabric has a design, each cut length must round up to a whole repeat, which adds fabric, sometimes a lot on large repeats. The widths shown cover the whole track; for a pair of curtains, split them, adding one width to a side if the total is odd.

Everything here is an estimate to help you buy with confidence, not a cutting plan. Buy around 10% extra for pattern matching, shrinkage and mistakes, and measure your window twice before ordering. All calculations run entirely in your browser.

Frequently asked questions

How much fabric do I need for curtains?: Multiply your track width by the fullness ratio, divide by your fabric width, and round up — that is the number of fabric widths. Multiply that by the cut length (your drop plus hem allowance) for the total. For example, a 240 cm track at 2× fullness on 137 cm fabric needs 4 widths.
What fullness ratio should I use?: Between 1.5 and 2.5 times the track width is typical. Pencil and pinch pleat headings look best at 2 to 2.5; eyelet headings work around 1.5 to 2. Below 1.5 curtains look flat, and above 2.5 they are very full and heavy.
Do I need extra fabric for a pattern repeat?: Yes. With a patterned fabric, every cut length must round up to a whole pattern repeat so the design lines up across widths, which adds fabric — sometimes a lot with large repeats. This calculator assumes plain fabric, so add the repeat allowance yourself.
Can I calculate in inches as well as centimetres?: Yes. Switch the units selector to inches or centimetres and enter every measurement in that unit. The result is shown in the same unit, with a rough metre or yard total to help you buy fabric off the roll.
How much extra fabric should I buy?: Around 10% more than the calculated total is sensible — it covers pattern matching, shrinkage after washing, and cutting mistakes. The calculator shows this +10% figure for you. Always measure your window twice before ordering.

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About Curtain Fabric Calculator

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