Sewing & Fabric Calculators
Curtain Fabric Calculator
Sewing your own curtains? This curtain fabric calculator turns your window width and finished length into the number of fabric widths to cut and the total yardage — including fullness for a proper gather, hem and header allowances, and pattern-repeat matching.
Last reviewed: June 2026
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Your result will appear here after you press Calculate.
Yardage is rounded up to the nearest 1/4 yard and assumes both panels are cut from the same fabric.
Formula used
The calculator builds the total from window width, fullness, and cut length:
- Flat fabric width = rod width × fullness ratio
- Fabric widths to cut = round up(flat width ÷ fabric width)
- Cut length = finished length + header + hem (rounded up to a full pattern repeat)
- Total fabric = widths × cut length
- Yardage = round up(total ÷ 36) to the nearest 1/4 yard
Worked examples
48-inch window, 84-inch curtains, 2× fullness, 54-inch fabric
A 48-inch rod at 2× fullness needs 96 inches of flat fabric — two widths of 54-inch fabric. Each cut is 84 + 16 = 100 inches, so you need about 5.75 yards.
Same window in a fabric with a 24-inch repeat
The 100-inch cut rounds up to 120 inches (five repeats), so the same curtains now need about 6.75 yards to keep the pattern matched across both panels.
How to use this calculator
- Measure your curtain rod width and the finished length you want the curtains to hang.
- Choose a fullness ratio — 2× is standard, 2.5–3× for pleated or sheer looks.
- Select your fabric width and set the header plus hem allowance.
- Enter the pattern repeat (0 for solids), then press Calculate.
Reference chart
| Header style | Recommended fullness |
|---|---|
| Rod pocket (casual) | 1.5× – 2× |
| Grommet / eyelet | 2× |
| Pencil pleat | 2× – 2.5× |
| Pinch / goblet pleat | 2.5× |
| Sheers | 2.5× – 3× |
Frequently asked questions
How much fabric do I need to make curtains?
It depends on the window width, the length, and how full you want the curtains. A standard 48-inch window with 84-inch curtains at 2× fullness needs about 5–6 yards of 54-inch fabric. Enter your numbers for an exact figure.
What is curtain fullness and what ratio should I use?
Fullness is how much wider the flat fabric is than the rod, which creates the gathered folds. Use about 2× for a standard look, 2.5× for pleated headers, and up to 3× for sheers. Lower fullness looks flat; higher fullness looks luxurious but costs more fabric.
How many widths of fabric do I need for curtains?
Multiply the rod width by your fullness ratio, then divide by the fabric width and round up. Wide windows usually need two or more widths per panel, seamed together. The calculator does this for you.
How much extra length do I add for hems?
Allow for a top header and a bottom hem. A common total is about 16 inches (for example, an 8-inch double bottom hem and a header allowance), but heavier drapes use more. Adjust the allowance field to match your header style.
Why does a pattern repeat use more fabric?
To match the design across panels and widths, each cut has to begin at the same point in the pattern, so the cut length is rounded up to a whole repeat. A large repeat can add a yard or more, especially across several widths.
Should I prewash curtain fabric?
If the fabric is washable and you plan to launder the curtains, prewash to prevent later shrinkage from pulling them short. Add a little extra yardage to allow for shrinkage, and press before cutting.