For a 200 cm rail with fullness 2 you need 400 cm of fabric width. With 140 cm wide fabric that is 3 widths, and with a height of 250 cm plus 25 cm for hems you need 8.25 metres of fabric in total.
How do you calculate curtain fabric?
A curtain (gordijn in Dutch) is never as wide as its rail, because it has to hang in folds. Multiply the rail width by the fullness factor to get the fabric width needed. For a 2 metre rail with fullness 2, that is 4 metres. Divide by the fabric width (140 cm), rounded up, for the number of widths. Then multiply the widths by the length of each, which is the height plus allowance for hems.
Choosing the fullness
| Fullness | Effect | Suits |
|---|---|---|
| 1.5 | Flat, few folds | Heavy fabrics, tight budgets |
| 2 | Nice full drape | Most curtains |
| 2.5 | Very full, luxurious | Light fabrics, large windows |
| 3 | Rich folds | Sheers and wave curtains |
Length of each width
Measure from the underside of the rail or pole down to where the curtain should end. Floor-length curtains normally stop 1 to 2 cm above the floor. Add about 10 to 15 cm for the bottom hem and 5 to 10 cm for the heading. The calculator uses 25 cm in total. Patterned fabric has a repeat that needs extra material, so order 10% more.
Several windows or a wide rail
- For a pair of curtains, split the widths between left and right, and round up each side to whole widths.
- With 280 cm wide fabric you can make a seamless curtain by turning the fabric, so the fabric width becomes the curtain height.
- Choose a rail that extends 10 to 20 cm beyond each side of the window so the curtains clear the glass when open.
Working on the same project? Calculate the Wallpaper Calculator and Laminate Flooring Calculator too, and use the Percentage Calculator to work out sale discounts.
How to use this calculator
- Measure the rail width and the height you want the curtain to hang.
- Choose the fullness: 2 is standard, higher gives a fuller curtain.
- Choose the fabric width, shown on the bolt (usually 140 cm).
- Press Calculate and order 10% extra for patterned fabric.
Key figures at a glance
| Fabric width needed | rail × fullness |
|---|---|
| Widths | needed ÷ fabric width, rounded up |
| Length per width | height + hems |
| Extra for pattern | 10% |
Frequently asked questions
Rail width × fullness ÷ fabric width gives the number of widths. Multiply by the length per width including hems.
Fullness 2 is standard. Choose 2.5 to 3 for fuller curtains or sheers.
Usually 1 to 2 cm above the floor. You can also let them pool on the floor or stop at the windowsill.
Clearly wider than the window, 10 to 20 cm per side, so curtains clear the glass when open.
Yes, allow about 10% extra and make sure the pattern matches on each width.