Curtain Fabric Width
Curtains must be wider than the window to hang in folds. Multiply window width by the fullness ratio; split in two for a pair. Ratio 1.5 gives a light gather, 2 is standard and 2.5 or more is generous.
Your numbers
Fabric width needed
360cm
Result
180cm
Difference
180cm
Formula
Fabric width needed = Window width × Fullness ratio
Poles usually extend 15–20 cm past the window each side, so the curtains clear the glass when open.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Window width (cm)The width to cover; measuring the pole is usually better. | 180 | 0 and up |
| Fullness ratio (×)How many times the window width in fabric; 2 is standard. | 2 | 1 ~ 4 |
Step by step
Quick reference table
Results when only Window width (cm) changes and everything else stays put.
| Window width (cm) | Fabric width needed (cm) | Result (cm) | Difference (cm) |
|---|---|---|---|
| 90 | 180 | 90 | 90 |
| 135 | 270 | 135 | 135 |
| 180 | 360 | 180 | 180 |
| 270 | 540 | 270 | 270 |
| 360 | 720 | 360 | 360 |
What each result means
| Result | At default values |
|---|---|
| Fabric width needed (cm)The fabric width needed to hang in folds. | 360 |
| Result (cm)What the formula gives back — the answer this page is for. | 180 |
| Difference (cm)The gap between two values — a quantity, not a rate. | 180 |
Common mistakes
Poles usually extend 15–20 cm past the window each side, so the curtains clear the glass when open.
Glossary
- Window width
- The width to cover; measuring the pole is usually better.
- Fullness ratio
- How many times the window width in fabric; 2 is standard.
- Fabric width needed
- The fabric width needed to hang in folds.
- Result
- What the formula gives back — the answer this page is for.
- Difference
- The gap between two values — a quantity, not a rate.
Frequently asked questions
Q. How is Curtain Fabric Width calculated?
Fabric width needed = Window width × Fullness ratio — Curtains must be wider than the window to hang in folds. Multiply window width by the fullness ratio; split in two for a pair. Ratio 1.5 gives a light gather, 2 is standard and 2.5 or more is generous.
Q. Can you walk through an example?
With Window width 180cm, Fullness ratio 2×, the answer is Fabric width needed 360cm.
Q. What do I need to enter?
Enter Window width, Fullness ratio. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Window width (cm) moves the answer to Window width (cm) 90 → Fabric width needed (cm) 180 and Window width (cm) 360 → Fabric width needed (cm) 720. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Poles usually extend 15–20 cm past the window each side, so the curtains clear the glass when open.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.