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Curtain and Drapery Fabric Calculator
Curtain yardage is a short calculation with one variable that catches people out: fullness. A flat panel that looks correct on the rail is not the same as a curtain with the fullness that makes it hang properly. This calculator works the yardage for pole pocket, grommet, tab top and ring headings, and it adds the extra lining fabric if the curtains need to be lined.
Curtain and Drapery Fabric Calculator
Yardage from window size, fullness and heading style, lined or unlined.
The track or pole span. Add 10 to 20 cm on each side for stacking.
Top of the heading to the finished hem.
How much fabric the heading gathers. This is the main variable.
Some headings need extra fabric above the finished drop.
Lining needs the same area as the face plus a seam allowance.
Two panels are usual for a single window.
Change any field, then press Enter again to recalculate.
Working out the curtain yardage
- Reading the window width and drop
- Applying fullness for the heading style
- Converting the finished size to cut size
- Adding the header allowance and side hems
- Adding lining fabric if the curtains are lined
Press the button to see the figures
Enter the window width and drop above 0.
Curtain yardage for one window
Yardage per panel
—
metres, face fabric
Total face fabric
—
metres for all panels
Lining needed
—
metres, if lined
Cut length per panel
—
metres from the bolt
Fabric width needed
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recommended minimum
Total incl. lining
—
metres of everything
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Fullness Is the Whole Calculation
Every other number in curtain making is straightforward. The one that decides how much fabric you need is fullness: how much the heading gathers the flat fabric. A 150 cm window at 1.5 times fullness gives a 225 cm finished panel; at 3 times it gives 450 cm. Same window, same rail, twice the cloth.
| Fullness | What it looks like | When to use it |
|---|---|---|
| 1.5x | Flat, crisp, every crease visible | Formal rooms, Japanese styling, flat panel curtains |
| 2x | Balanced, folds at the heading | Most living rooms and bedrooms; the safe default |
| 2.5x | Full, soft vertical folds | Everyday curtains, longer drops, warm rooms |
| 3x | Very full, deep folds, expensive | Hotel rooms, blackout curtains, formal drapery |
Fabric Width Decides Whether the Drop Fits
After fullness, the constraint is fabric width. A finished drop of 230 cm cannot be cut in one piece from a 140 cm fabric, so the curtain is either made in two widths stitched vertically, or in a full-width fabric at 280 to 300 cm.
The two-width route is normal and gives slightly different results from a full-width panel because the two halves hang side by side rather than stacking. Full-width fabric is more expensive per metre and there is less choice, but it is the only way to get a seamless tall panel. Curtain fabric is one of the places where 150 cm widths are actually the standard, because that is the width mills weave for this purpose.
Lining and Why It Is Worth It
Lining serves three purposes: it stops the sun fading the face fabric, it makes the curtain hang better because the lining is a stiffer fabric carrying the weight, and it improves the insulation. Part lining, covering the top two thirds, is a reasonable compromise and is common on bedroom curtains.
Lining uses less yardage than the face because it is cut narrower, but it needs the same finished area. Allow about 35 cm extra for seams. A lined pair uses roughly 1.5 times the yardage of an unlined pair, which is the factor people most often forget when budgeting.
Drop Measurement Details
Measure the drop from the top of the finished heading, not from the rail or pole. On a pole pocket curtain the rail is usually 6 to 8 cm above the top of the curtain so the pocket sits over it, and that difference comes out of the drop. Leave the hem 12 to 15 cm above a radiator or a floor that may move.
Frequently Asked Questions
How much fabric do I need for curtains?
Measure the window width, multiply by the fullness you want, and add 20 to 30 cm for the heading and side hems. For a standard 150 cm window at 2 times fullness in two panels, expect about 3 metres of 140 cm fabric per panel including lining, so around 6 metres in total.
What fullness should curtains have?
Twice is the standard for most rooms. Flat panel and formal styles use 1.5, everyday full curtains use 2.5, and hotel or blackout styles use 3. Fullness is what makes a curtain hang in folds rather than hang flat, so it is worth deciding deliberately.
Can I use 140 cm fabric for long curtains?
Yes, by making the curtain in two widths stitched together. It is the normal approach and many ready-made curtains are built this way. The only thing you lose is the seamless look of a full-width panel, and full-width fabric for tall drops is expensive and hard to find.
How much extra fabric for a pole pocket heading?
A pole pocket needs the fabric to be wide enough to slide over the rail, so add the pocket depth to the drop and allow 6 to 8 cm so the curtain hangs below the rail. Ring and tab headings need more: add 15 to 20 cm for the heading tape and tabs above the finished top.
Do curtains need lining?
It depends on the room and the fabric. Lining prevents fading, makes the curtain hang better, and improves insulation, so it is worth it for bedrooms and for any window in direct sun. Part lining the top two thirds is a common compromise for less formal rooms.
Why does my curtain look flat even though I bought 2x fullness?
Usually the heading is gathering less than you think, or the fullness is concentrated in a very short header tape. Fullness only works if it is distributed along the full width of the heading. Another common cause is a fabric with too much body, which stands away from the wall instead of falling in folds.
Weight matters for long drops: the fabric GSM chart shows which weights hang well at 250 cm and above.
Related upholstery work: the cushion and pillow calculator covers the smaller home-sewing projects.