SewShape · Tools

Back-Pleat Curtain Calculator

Start with the width you want one curtain to occupy when parked. The calculator uses the pleats, allowances and shrinkage to estimate the fabric length to buy.

01 · Parked shape

Set the curtain width

Parked width per curtain Centimetres. The calculator assumes a fixed 30% parked-to-working ratio. Identical curtains Each curtain uses the same parked width and allowances.

02 · Pleat rhythm

Choose the front and back proportion

Front pleat target Centimetres. The run begins and ends with a front pleat.

Front ÷ back coefficient 1.25

A higher coefficient makes the back pleat narrower.

03 · Fabric, drop and allowances

Allowance fields are the total fabric used. For a double hem, include both turns.

Finished curtain drop Usable fabric width Net centimetres available after selvedges and any standard-drop joining loss.

Fabric direction Standard drops Sideways / railroaded

Shrinkage Percent applied equally to width and drop. Return allowance Left side-hem allowance Right side-hem allowance Bottom-hem allowance Buckram height Top-turn allowance

Buy at least 6.3 m total for 1 curtain, rounded up to the next 0.1 m

2 standard drops × 3.13 m

Calculated minimum: 6.26 m

Standard-drop estimate: the usable width is divided into whole joined drops.

Target working width 150.0 cm

Actual working width 152.0 cm

Marking Front 8.0 / Back 6.4

Pleats 19 front / 18 back

Clean fabric width 267.2 cm

Cut drop before washing 312.8 cm

Before buying fabric

This calculator is for plain or non-matched fabric. It does not include pattern-repeat matching, half-drop repeats, trimming waste, lining or interlining.

It estimates new fabric to buy. It does not plan a layout around fabric you already own.