To work out curtain fabric in meters, multiply the track or pole width by your fullness ratio, divide by the width of your fabric, and round up to the next whole number — that gives you the number of fabric widths to cut. Each cut length is your finished drop plus a hem and heading allowance, usually 20 to 25 cm combined for most curtain headings. The total fabric in meters is widths multiplied by cut length, with roughly ten percent extra added on top to cover shrinkage, cutting mistakes and pattern matching.
The first number, the fabric widths, is the one most people get wrong — round up rather than down, because three widths would leave the curtain too flat to pleat properly. The other thing to remember is that this whole process assumes plain fabric. With a pattern repeat, each cut length must round up to a whole repeat, which adds more fabric — sometimes a lot on large repeats. The Curtain Fabric Calculator runs all three steps live as you type so the meter total is always visible while you change inputs.
Why curtain fabric is sold by widths, not square meters
Fabric is sold off the roll at a fixed width — usually somewhere between 90 cm and 150 cm for dress and decor cloth. Curtains are made by joining several of these vertical strips, called widths or drops, side by side until they cover the pole. Because of that, you cannot measure curtain needs in square meters the way you would for a sofa cover or tablecloth; you need to know how many widths to cut and how long each one needs to be.
Two numbers from the fabric itself decide almost everything: the usable width on the bolt (printed on the selvedge or the product page) and the price per metre, which is for length only. The width is fixed, so the question is always how many drops you need and how long each drop is. That is why every curtain fabric formula in the world starts with width, not area, and why the answer to "how many meters of fabric" is really a multiplication of widths by a length.
The selvedge edges are usually trimmed off before sewing, which is why the usable width is a centimetre or two less than the full bolt width. Trust the figure on the product listing rather than measuring the bolt yourself.
The formula for curtain fabric in meters
The full calculation is six short steps. Run them in order and you can size any window without a calculator; if you would rather skip the arithmetic, the Curtain Fabric Calculator runs all of them live as you type.
- Measure the track or pole width end-to-end in centimetres. For a pair of curtains, this is the whole pole, not just one side.
- Measure the finished drop from the hook or track down to where the hem should sit. If you want the curtain to brush the floor, end the measurement there; if you want it to puddle, add the extra length yourself.
- Pick a fullness ratio for your heading style — 1.5 to 2.5 is the working range, with 2 the most common starting point.
- Find the fabric width on the bolt label or the product listing. Common decor widths are 137 cm, 140 cm and 150 cm.
- Work out how many widths to cut: track width multiplied by fullness ratio, then divided by fabric width, then rounded up to the next whole number.
- Work out each cut length: finished drop plus the hem and heading allowance (typically 20 to 25 cm). Total fabric in metres equals widths multiplied by cut length, then add 10%.
Choosing the right fullness ratio
Fullness is what makes a curtain look like a curtain instead of a hanging sheet. Multiply the track width by it and you get the total flat fabric that needs to span the pole when the heading is drawn up into pleats. Too little and the curtain hangs flat; too much and it gets heavy and uses far more fabric than needed.
| Heading style | Typical fullness ratio | Look and feel |
|---|---|---|
| Pencil pleat | 2 to 2.5 | Soft, traditional gathers |
| Pinch pleat (double or triple) | 2 to 2.5 | Formal, structured drapes |
| Eyelet | 1.5 to 2 | Modern, wide, even folds |
| 1.5 to 2 | ||
Below 1.5 the curtain will look flat and mean, with no body to drape. Above 2.5 you are paying for extra fabric for the sake of it, and the heading tape may struggle to gather the volume. If you are unsure, 2 is a safe middle value that works with most heading tapes and most decor weights.
Setting the hem and heading allowance
The finished drop you measured is the curtain after it has been sewn. To get the cut length, you have to add the turnings — the fabric folded over at the top to form the heading and the deeper double fold at the bottom that becomes the hem. The combined allowance is normally between 20 and 25 cm, but the exact number depends on two things.
At the top, a few centimetres folded under the heading tape is usually enough — most tapes are 5 to 8 cm deep, so a 5 to 8 cm fold plus the tape gives a clean finish. At the bottom, a 10 to 15 cm double-fold hem is standard for heavier decor weights, while a 7 to 10 cm hem is fine for lightweight sheers. A combined allowance of 25 cm works well for medium-weight fabric with a deep hem; trim it to 20 cm for lighter cloths or curtains where the hem is shallow on purpose.
The heading allowance also covers any extra fabric the tape needs to sit inside the fold. Pencil pleat tapes with deep pockets can take a touch more; a simple rod-pocket header takes very little. If you know your heading tape, set the allowance to match it. If not, 25 cm is a safe default that comes out even on most medium-weight decor fabric.
Worked example in meters: a 240 cm pole
Let's run through a full calculation from start to finish using values that real curtains get.
- Track width: 240 cm
- Finished drop: 165 cm (a typical sill-length window)
- Heading: pencil pleat, fullness 2
- Fabric width: 137 cm
- Hem and heading allowance: 25 cm
Number of widths: 240 multiplied by 2 = 480 cm of flat fabric needed; 480 divided by 137 = 3.5, which rounds up to 4 widths. You cannot buy half a width, so 4 is the correct answer — 3 would leave the curtain too flat to pleat properly.
Cut length per width: 165 + 25 = 190 cm.
Total fabric off the roll: 4 multiplied by 190 = 760 cm, which is 7.6 metres.
Plus 10% for shrinkage, pattern matching and mistakes: 7.6 multiplied by 1.10 = 8.36 metres. Round that up to the next half metre when you order, which gives 8.5 metres off the roll.
Where manual calculation goes wrong
Three things trip people up even when the formula is in front of them.
Forgetting to round up the widths. The widths step produces a decimal almost every time. Round up, never down — 3.5 widths becomes 4 widths, not 3. The whole point of the round-up is so the heading tape has enough flat fabric to gather into a full-looking curtain.
Ignoring the pattern repeat. The formula above assumes plain fabric. With a printed or woven design, each cut length has to round up to a whole repeat of the pattern so the design lines up across widths. A small 10 cm repeat costs very little extra; a 64 cm floral repeat can add a metre or more per drop. Add the repeat allowance yourself or measure twice before ordering.
Splitting a pair of curtains unevenly. The widths number covers the whole track. For a pair of curtains, split it between the two panels — and if the total is odd, add one extra width to one side so each panel meets in the middle without a gap.
All calculations run entirely in your browser on the Curtain Fabric Calculator page, so any number you tweak updates the metre total the moment you change a field.