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WIN-J · EVERYDAY & WORK TOOLS

Curtain size and fabric calculator

Calculate equal curtain panels, joining widths and fabric metres from rail width, fullness and finished length. Include seam allowances and export the cutting breakdown.

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Input settings

The selected unit applies to rail width, finished length and usable bolt width. All seam and hem allowances are cm; purchase increment is m. Changing units reinterprets existing numbers.

Enter the installed rail width rather than the bare window width. Panels are equal. Use plain fabric in vertical drops; usable bolt width excludes unusable selvedges. Enter the total fabric consumed by each hem, including folds.

How to use

  1. Measure the installed rail width and desired finished curtain length.
  2. Choose fullness, equal panel count and usable fabric width.
  3. Enter side hems, joining seam allowances and top/bottom allowances in cm.
  4. Review the cutting detail and apply extra length and purchase increment.

Example

A 300 cm rail, 2× fullness and 2 curtains need 300 cm flat width per curtain. A 150 cm bolt with 4 cm side hems and 1.5 cm joining allowances needs 3 widths per curtain. Finished length 240 + top 10 + bottom 20 cm gives 6 cuts × 2.7 m = 16.2 m.

Method and limitations

Total flat width = rail width × fullness, divided equally among panels. With n widths per panel, usable width = n × bolt width − 2 × joining allowance × (n − 1) − 2 × side-hem consumption. Use the smallest whole n meeting the target. Each cut = finished length + top + bottom allowances. Base fabric = cut length × widths per panel × panel count. Add the extra percentage once, then round up to the purchase increment. Assumes vertical full-width cuts in plain fabric. Pattern matching, selvedge removal, shrinkage, crosswise cutting, lining and sewing costs are excluded. Limits: 1–20 equal panels, fullness 1–4 and 2,000 cuts.

Frequently asked questions

Does width mean window width?

Use the full installed rail or pole width, including your chosen side coverage, before applying fullness.

Can a seam add a whole fabric width?

Two bolt widths may become too narrow after joining seams and outer hems, requiring another whole width.

Does extra length automatically correct shrinkage?

It only adds the entered percentage to base length. Plan fabric-specific shrinkage, washing and pattern matching separately.

Related tools

References