BYTETOOLS

Curtain Fabric Calculator

Work out curtain fabric from track width, drop and fullness: number of widths, cut length rounded to whole pattern repeats, lining yardage and total cost.

525.0
Flat width needed (cm)
4
Widths of fabric
256.0
Cut length per width (cm)
10.24
Face fabric (m)
2.00
Widths per panel
4
Repeats per drop
9.92
Lining (m)
2.62×
Fullness actually achieved

Cut list and cost

ItemPiecesCut length (cm)Total (m)Cost
Face fabric4256.010.24$307.20
Lining4248.09.92$89.28
Total$396.48

Pattern matching adds 8.0 cm to every drop — 32.0 cm across 4 widths. Keep the offcuts: they are exactly the right length for tie-backs and a matching cushion.

Widths = (track width × fullness + returns + overlap) ÷ the usable fabric width, always rounded up — half a width still costs a whole width. Cut length = finished drop + hem + heading allowance, rounded up to a whole number of pattern repeats so the design lines up across every join. A 200 cm track at 2.5× fullness on 137 cm fabric needs 4 widths, and a 220 cm drop with a 20 cm hem and 8 cm heading on a 64 cm repeat cuts at 256 cm — 10.24 m of fabric in total. Measure the track, never the window, and measure the drop in three places: floors are rarely level. Estimates only.

What is the Curtain Fabric Calculator?

The ByteTools Curtain Fabric Calculator does the geometry people get wrong by hand. Number of widths is the track width multiplied by your fullness ratio, plus returns and the centre overlap, divided by the usable fabric width and rounded up — half a width still costs a whole width, which is exactly why the rounding matters.

  • Widths from track width × fullness plus returns and overlap, always rounded up
  • Cut length rounded to whole pattern repeats, with the offcut per drop shown
  • Heading presets that set fullness and heading allowance automatically
  • Lining yardage costed separately at the unmatched cut length
  • Fullness actually achieved after rounding, so you can see what you really get
  • Copyable cut list and a cost table; all maths runs locally in your browser

How to use the Curtain Fabric Calculator

  1. 1

    Pick centimetres or inches, your currency, and the heading style — pencil pleat, pinch pleat, eyelet, wave or tab top.

  2. 2

    Enter the track or pole width and the finished drop, and adjust the fullness ratio and heading allowance if you are using a custom heading.

  3. 3

    Set the fabric width, any selvedge you trim, the hem allowance and the pattern repeat (0 for a plain fabric).

  4. 4

    Add the returns, the centre overlap, the number of panels and how many of them are lined.

  5. 5

    Read the widths, cut length and total fabric, enter fabric and lining prices, and copy the cut list.

About the Curtain Fabric Calculator

The ByteTools Curtain Fabric Calculator does the geometry people get wrong by hand. Number of widths is the track width multiplied by your fullness ratio, plus returns and the centre overlap, divided by the usable fabric width and rounded up — half a width still costs a whole width, which is exactly why the rounding matters.

Cut length is the finished drop plus hem and heading allowances, rounded up to a whole number of pattern repeats so the design lines up across every join. A 200 cm track at 2.5× fullness on 137 cm fabric needs 4 widths, and a 220 cm drop with a 20 cm hem and 8 cm heading on a 64 cm repeat cuts at 256 cm — 10.24 m of fabric.

Heading styles set sensible default fullness and heading allowances, or you can enter your own. Lining is costed separately at the raw cut length since it has no pattern to match. Everything runs in your browser with nothing uploaded — measure the track rather than the window, and measure the drop in three places because floors are rarely level.

Frequently asked questions

How much fabric do I need for curtains?

Multiply the track width by your fullness ratio, add returns and overlap, divide by the fabric width and round up to get the number of widths. Then multiply that by the cut length — finished drop plus hem plus heading — and you have the total fabric.

What fullness ratio should curtains be?

Between 2.0 and 2.5 times the track width for most headings. Pencil pleat looks best at 2.5, pinch pleat works at 2.0 to 2.5, eyelet at around 2.2, and tab top can go as low as 1.5. Below 2.0 the curtain looks skimpy when it is drawn.

How do I allow for a pattern repeat in curtains?

Round every cut length up to the next whole multiple of the repeat, so each width starts at the same point in the design and the pattern matches across the joins. On a large repeat this can add a substantial amount to every drop, which is what the offcut figure here shows.

Should I measure the window or the track for curtains?

The track or pole, always — curtains hang from the track, not the window, and a track usually extends well past the reveal so the curtains can stack clear of the glass. Also measure the drop in three places across the width, because floors and sills are rarely level.

What is the return and overlap on a curtain?

The return is the bit of fabric that wraps from the front of the track back to the wall at each end, blocking light down the sides. The overlap is where the two leading edges cross in the middle of a pair. Both add to the flat width you have to buy.

How much hem allowance do curtains need?

A double hem is standard, so allow twice the finished hem depth — 20 cm for a 10 cm double hem, or 8 inches for a 4 inch one. Heading allowance depends on the style: about 8 cm for pencil pleat, closer to 20 cm for pinch pleat with buckram.

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