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YardageLab

Curtain Fabric Calculator

Calculate curtain fabric including fullness, header, hem and pattern repeat for a pair of panels.

Units
in
in
Fullness ratio
pcs
Fabric width
in
in
in

Vertical repeat of a patterned fabric. 0 for plain fabric.

Curtain fabric to buy

5.75yd

2 fabric widths seamed together

Exact math

5.56 yd

Buy (rounded up)

5.75 yd

Gathered width
96 in
Fabric widths
2
Cut length
100 in
2 fabric widths × 100 in
Assumptions used
Fullness ratio
2×
Gathered width
96 in
Header + hem allowance
16 in
Pattern repeat
none
Fabric widths seamed
2
Purchase rounded up to
0.25 yd

Methodology

How the curtain calculation works

Curtains need extra width to gather nicely and extra length for the header and hem:

  • Gathered width = track width × fullness ratio
  • Fabric widths = gathered width ÷ fabric width (rounded up)
  • Cut length = finished drop + header + hem
  • Total fabric = fabric widths × cut length

If your fabric has a pattern repeat, each cut length is rounded up to a whole number of repeats so the pattern matches across seams. The total is converted to yards and rounded up to the next quarter yard.

See it in numbers

Worked example

A 48″ window, 84″ drop, 2× fullness, 54″ fabric, 8″ header + 8″ hem:

  • Gathered width = 48 × 2 = 96″
  • 96″ ÷ 54″ = 1.8 → 2 fabric widths
  • Cut length = 84 + 16 = 100″; 2 × 100″ = 200″
  • 200″ ÷ 36 = 5.56 yd → buy 5.75 yd

Reference

Fullness ratios

RatioLookBest for
1.5×Light gatherSheers, casual panels
2.0×Standard gatherMost pencil-pleat curtains
2.5–3.0×Full, luxuriousPinch pleat, formal rooms

Header and hem allowances of 6–10″ each are common; deeper hems drape better on long drops.

Frequently asked questions

Does “panels” mean a pair of curtains?
Panels is the number of finished curtain pieces (2 for a typical pair). The tool never uses fewer fabric widths than panels, so each panel gets at least one width.
How do I handle a patterned fabric?
Enter the vertical pattern repeat. Each cut length is rounded up to a full repeat so the motif lines up where widths are joined — this can noticeably increase the fabric needed.
What about width lost to side hems?
Fullness at 2× or more generally absorbs side hems. For very precise projects, add a few inches to the window width to cover side turnings.

Transparency

Sources & assumptions

  • Gathered width = window width × fullness; side hems are absorbed by fullness.
  • Cut length = drop + header + hem, rounded up to a full pattern repeat when given.
  • At least one fabric width per panel.
  • Purchase yardage rounds up to the next ¼ yard.

Keep planning

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Last reviewed August 23, 2026

Found an error? Tell us — every formula is human-reviewed.