Curtain fabric calculator
How much fabric do your curtains need? Enter the measurements and the curtain type. The calculator works out the number of widths, the cut length per width and the total fabric in metres — hems included, with an optional pattern repeat.
Measurements
Result
Enter the track width, drop and fabric width to calculate the fabric usage.
How curtain fabric usage is calculated
The fabric for a curtain comes from three steps. First the width: track width × fullness, plus the side allowance on both sides. Divide that by the width of your fabric to get the number of widths — always rounded up. Next the cut length per width: the drop plus the allowance for the bottom hem and the heading. Finally, multiply the cut length by the number of widths.
Worked example
A wave curtain for a 300 cm track, with a 260 cm drop, a fabric 140 cm wide and a 32 cm pattern repeat. At 2.0 fullness and a 5 cm side allowance on each side, the flat fabric width is 610 cm; divided by 140 cm that gives 4.36 — so five widths. The cut length per width is the 260 cm drop plus a 20 cm bottom hem and 12 cm for the heading, 292 cm in total. Round that up to a whole number of 32 cm repeats: 320 cm. Five widths × 320 cm is 16 metres of fabric.
Without a pattern, 5 × 292 cm, or 14.6 metres, would have been enough. That difference of more than a metre is exactly why the pattern repeat belongs in the quote — not as a rounding margin after the fact.
Where it goes wrong
The most common mistakes: working from the window width instead of the track width, forgetting the pattern repeat on a patterned fabric, rounding the number of widths down, and forgetting the lining as a separate item. Each of these four leaves you short of fabric — and means reordering from a different dye lot, with a colour difference as the result.
Frequently asked questions
How do I work out the number of fabric widths?
Divide the flat fabric width you need (track width × fullness, plus side allowance) by the width of your fabric and round up. There is no such thing as half a width: at 3.4 widths, you order four.
What is a pattern repeat and how do you allow for it?
The pattern repeat is the height at which the design repeats. With a patterned fabric, you round the cut length per width up to a whole number of repeats, so the pattern lines up at the same height across every width. That costs extra fabric, especially with a large repeat.
How much should I allow for hems and seams?
As a rule, allow 15 to 20 cm for the bottom hem and 10 to 15 cm for the top hem or heading tape, plus 2 to 3 cm for each seam between widths. For a weighted hem or a double hem, allow more.
Does lining count towards the fabric usage?
Yes, but as a separate item. The lining follows the same width calculation, usually with the same fullness, but with no pattern repeat allowance and a shorter length, as lining usually hangs a few centimetres shorter than the main fabric.
Curtain fullness calculator
Work out the fabric width you need from the track width and curtain type.
Calculate it automatically with Gordana
In Gordana you enter the measurements once — fabric usage, price and quote are generated automatically, per room and per customer.
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