Curtain / Drapery Fabric Calculator
Work out exactly how many yards of fabric a curtain or drapery treatment needs from your rod width, desired length, fullness ratio and fabric details — including how much a pattern repeat adds.
How this calculator works
The calculator works out the total fullness width the fabric has to cover, divides that by the fabric's bolt width to get how many full widths of fabric are needed, then works out how long each cut piece has to be to include hems and pattern matching:
total_fabric_width_needed = rod_width × fullness_ratio panels_by_width = ceil(total_fabric_width_needed / fabric_bolt_width) panel_length_with_allowance = curtain_length + hem_allowance + pattern_repeat yards_per_panel_width = ceil(panel_length_with_allowance / 36) total_yards = panels_by_width × yards_per_panel_width
"Fabric widths needed" is a technical yardage term — how many loom-widths of fabric, sewn side by side, are required to reach the full fullness across the whole rod. It's independent of how many hanging panels you split that fabric into; the "widths per panel" figure below is a reference only and doesn't change the total.
Worked example
A 60 in rod, 84 in curtain length, 2× fullness, 54 in fabric, 12 in hem/heading allowance, no pattern repeat:
- Total fullness width: 60 × 2 = 120 in.
- Fabric widths: ceil(120 ÷ 54) = 3 widths.
- Cut length: 84 + 12 + 0 = 96 in.
- Yards per width: ceil(96 ÷ 36) = 3 yd.
- Total: 3 × 3 = 9 yards.
Add a 24 in pattern repeat to the same job and the cut length rises to 84 + 12 + 24 = 120 in, needing 4 yd per width instead of 3 — total yardage jumps from 9 to 12 yards, even though the finished curtain size hasn't changed at all.
Fullness ratio guide
| Ratio | Look |
|---|---|
| 1.5× | Minimum, relatively flat when closed |
| 2× – 2.5× | Standard, visible folds open and closed |
| 3× | Very full, luxurious, uses significantly more fabric |
Measuring your window
- Rod width — measure the installed or planned rod length, not the window opening itself.
- Curtain length — measure from where the rings or rod pocket actually sit down to your target hem line (sill, floor, or puddle — see the FAQ below).
- Bolt width — check the fabric's actual usable width, which is often narrower than the listed width once selvage is trimmed.
- Pattern repeat — check the fabric label; large motif prints can add significant yardage.
Frequently asked questions
What fullness ratio should I use?
1.5× is the minimum, often used for sheers, and looks relatively flat when closed. 2× to 2.5× is standard for most drapery, giving visible folds. 3× is very full and luxurious, using considerably more fabric.
How much extra fabric goes to hems and headers?
About 8 to 12 inches combined is typical — 4 to 8 inches for the bottom hem, 3 to 6 inches for the top heading. Heavier or lined fabrics often need a bit more.
How does pattern repeat change yardage?
It adds directly to the cut length per fabric width, since each width has to start at a matching point in the pattern. Large motifs can meaningfully increase total yardage without changing the finished curtain size.
What are standard curtain lengths — sill, floor, or puddle?
Sill length ends at the windowsill. Floor length just grazes the floor and is the most common choice. Puddle length adds 1 to 6 inches or more pooling on the floor for a dramatic look. Measure from the rod, not the window trim.