Estimate how much curtain fabric you need for a window, patio door, or full wall treatment. Enter your measurements, fullness, and allowances, then click calculate.
How this curtain fabric calculator works
This calculator estimates the total fabric needed by combining your window width, preferred fullness, and curtain drop. It then adds practical sewing allowances like heading and hem, and can account for a pattern repeat so your motifs line up correctly.
The logic is simple:
- Calculate total finished curtain width using your selected fullness ratio.
- Convert that width into the number of full fabric widths required.
- Calculate cut length per width (drop + heading + hem).
- Round up cut length to pattern repeat, if needed.
- Multiply widths by cut length and add waste allowance.
Measurements to prepare before buying fabric
1) Track or pole width
Measure the full width of your installed track or pole, not just the glass width. This is the finished span your curtains must cover.
2) Finished drop
Decide where curtains will end: sill, below sill, floor, or puddle. Measure from top fixing point down to that final hem location.
3) Fabric width
Most drapery fabrics are around 137 cm (54 in) wide, but this varies. Use usable width if selvages or defects reduce effective width.
4) Fullness ratio
Fullness controls how luxurious the folds appear:
- 1.5x — light, modern look
- 2.0x — standard and balanced
- 2.5x+ — rich, formal drape
Example calculation
Suppose your track width is 240 cm, drop is 220 cm, fullness is 2.0, fabric width is 137 cm, heading allowance is 10 cm, and hem allowance is 20 cm.
- Finished width needed: 240 × 2.0 = 480 cm
- Fabric widths needed: 480 ÷ 137 = 3.5 → round up to 4 widths
- Cut length per width: 220 + 10 + 20 = 250 cm
- Total before waste: 4 × 250 = 1000 cm = 10.0 m
- If adding 10% waste: 11.0 m recommended
This is why “eyeballing it” often causes under-buying—width count and pattern alignment add up quickly.
Pattern repeat and directional prints
If your fabric has a repeat (florals, damask, geometric motifs), each drop is usually rounded up to the next repeat increment. Even a 32 cm repeat can significantly increase yardage, especially across multiple widths.
Directional prints and one-way pile fabrics (like velvet) should all run the same direction. This can reduce layout flexibility, so keep a buffer allowance.
Common mistakes to avoid
- Forgetting to include heading and hem allowances.
- Using window width instead of track/pole width.
- Ignoring pattern repeat when matching across panels.
- Not rounding up to practical buying increments (e.g., nearest 0.5 m).
- Skipping extra margin for shrinkage, errors, or future repairs.
Buying tips for better results
Buy a little extra
Even with a calculator, add a safety margin. Dye lot changes can make later top-ups look mismatched.
Check care and shrinkage
Natural fibers can shrink. If pre-washing is required, do so before cutting—or factor extra length in your estimate.
Plan lining at the same time
Lining often uses similar width logic but can have different hem/heading assumptions. Calculate main and lining fabric separately for accuracy.
FAQ
How much fabric do I need for two curtain panels?
Use the calculator with panels set to 2. It will estimate total widths and suggest how they can be split across both panels.
Should I measure in inches or centimeters?
Either works. Select your unit in the calculator and it converts internally to produce totals in both meters and yards.
What fullness is best for pinch pleat curtains?
Most pinch pleat styles look best around 2.0x to 2.5x fullness, depending on fabric weight and desired luxury level.
Bottom line: A reliable curtain fabric calculation saves money, avoids delays, and gives your finished curtains the fit and fullness you intended. Use the calculator above before placing your order.