Windows & Curtains
Curtain Fabric Calculator
Estimate how much fabric your curtains need. Enter the track width, the fullness you want and the finished length, and we calculate total fabric including hems and pattern repeat.
Last updated: June 2026
How curtain fabric quantity is calculated
Curtain fabric calculation depends on four variables: the track width, the fullness ratio, the cut drop (finished length plus hems), and the fabric width. If there is a pattern repeat, every cut length must be rounded up to the next full repeat so the design aligns across panels.
Formula used
Cut drop = finished length + hem allowance
If pattern repeat > 0: cut drop = ceil(cut drop / repeat) × repeat
Widths per panel = ceil((track width × fullness / panels) / fabric width)
Total metres = widths per panel × panels × cut drop / 100 × 1.10
Worked examples
Example 1 — 150 cm track, 2.0× fullness, 230 cm drop, 2 panels: Total fabric width = 300 cm; 2 widths per panel × 2 panels × 260 cm = 1040 cm = 10.4 m + 10% = 11.4 m.
Example 2 — 200 cm track, 1.5× sheer, no repeat: 2 widths per panel × 2 × 2.9 m = 11.6 m × 1.1 = 12.8 m.
How to use this calculator
- Measure the track or rod width.
- Use the Curtain Length Calculator to find the finished drop.
- Select fullness ratio based on heading style.
- Enter hem allowance and pattern repeat if applicable.
Fullness ratio guide
| Fullness | Heading style | Fabric weight |
|---|---|---|
| 1.5× | Eyelet, tab top | Light / sheer |
| 2.0× | Pencil pleat, eyelet | Medium |
| 2.5× | Pinch pleat, box pleat | Medium / heavy |
| 3.0× | Goblet pleat | Lightweight only |
Notes & limitations
Always buy extra fabric. Related: Curtain Length Calculator.
Frequently Asked Questions
What fullness ratio should I use?
1.5× is standard for sheer or lightweight fabrics. 2× is the most common choice for a full, professional look with pencil pleat heading. 2.5–3× gives very generous gathers, typical of pinch pleat curtains.
How much extra fabric should I buy for pattern matching?
The calculator adds the pattern repeat to each cut length so repeats align across panels. We also include a 10% contingency. For large repeats over 30 cm, consider buying an additional half-repeat extra.
What is hem allowance and how much do I need?
Hem allowance covers the top heading plus the bottom hem. A standard allowance is 20–30 cm total: roughly 10–15 cm at the top and 10–15 cm at the bottom.
How many panels do I need for one window?
Most windows use two panels (one for each side). Single panels are used for a modern asymmetric look or narrow windows.
What fabric width should I choose?
Standard furnishing fabric is 137–150 cm wide. Wide-width (280–300 cm) fabric is designed for full-height curtains with minimal horizontal seams.