How much fabric you need for curtains

For a curtain that hangs well, covering the window width is not enough: the fabric is gathered, so you need much more of it. It is also bought in full widths, as wide as the roll, and if it has a pattern it must be cut so the design matches. This calculator tells you how many metres to buy, how many widths to cut and the fullness you will actually get.

How the calculation works

• Width needed: track or pole, plus overlaps and returns, times the chosen fullness.
• Widths: the width needed divided by the fabric width, rounded up to full widths.
• Cut: finished drop plus hems and heading; with a pattern it is rounded up to a multiple of the repeat.
• Metres: widths × cut length.
• Effective fullness: the width of the full widths divided by the width to cover.

Which fullness to choose

Fullness is the ratio between the fabric width and the width of the closed curtain. Around 1.5 gives light folds; 2 is the classic choice for many curtains; 2.5-3 gives the full look typical of sheers. The heading tape or hanging system may call for a specific fullness: check its instructions.

Examples by track width

Fullness 2, 140 cm fabric, 250 cm finished drop, 30 cm of hems and heading, 10 cm of overlaps:

With full widths the real fullness is almost always a little higher than the one chosen. If the result is too full, you can use one width fewer or cut one down.

Fullness rises in steps

200 cm track, same data:

On this track, fullness 1.5 and 2 need the same fabric: three full widths. You may as well choose 2 and get richer folds for the same price.

The pattern repeat

With a pattern, every width must start at the same point of the design, so the cut length is rounded up to a multiple of the repeat. Same data, three widths:

The reading bands

• Below 1.5: an almost flat curtain, suited to heavy fabrics or a minimal look.
• 1.5 to 2: light folds.
• 2 to 2.5: full, even folds, the classic choice.
• Above 2.5: a very full curtain, typical of sheers.

Limits of the calculator

The calculation does not include side hems on each width or the seams between widths: if they matter, add them to the overlaps. It does not apply to railroaded fabrics, which are wide enough to be turned and cut along the curtain width. Always buy a little extra, especially with large patterns or fabrics that shrink when washed.

Frequently asked questions

How much fabric for a 2-metre curtain?

With fullness 2, 140 cm fabric and a 250 cm finished drop with 30 cm of hems, you need 3 widths cut at 280 cm: 8.40 m.

What is curtain fullness?

The ratio between the fabric width and the width of the closed curtain. With fullness 2 you use twice the width to cover.

Which fullness should I choose?

Often 2 for standard curtains, 1.5 for a lighter look and 2.5-3 for sheers. The heading tape may specify one.

Why is effective fullness different from the one chosen?

Because fabric is bought in full widths: rounding up makes the total width a little larger.

What is a pattern repeat?

The distance after which the design repeats vertically. Each width must be cut to a multiple of the repeat so the pattern matches.

How much should I add for hems and heading?

It depends on the make-up: often 20-35 cm in total for the bottom hem and heading. Check the tape instructions.

What are overlaps and returns?

The overlap of the two curtains in the middle and the part that turns around the ends of the track.

How are widths split for a pair of curtains?

Half on each side; if the number of widths is odd, one width is split in half.

Does it work for railroaded fabric?

No: railroaded fabric, as wide as the curtain drop, is cut along the width and calculated differently.