Curtain Fabric Calculator

How to use

1. Measure your track or pole and type it into 'Window/track width (cm)' - use the track, not the window glass.
2. Enter 'Drop length (cm)' measured from the top of the track down to your chosen finish point.
3. Pick 'Fullness': 1.5x for light curtains, 2x for the standard gathered look, 2.5x for deep luxury folds.
4. Set 'Fabric width (cm)' to your bolt width - 140 cm is the common default.
5. Read 'Widths (panels)' to see how many drops to cut, and 'Fabric needed' for the total metres.
6. Add extra length for pattern repeats or bulky headings, then buy all the fabric in one batch so the dye lot matches.

About this tool

Curtains need 1.5–2.5× the track width for proper gathering. The tool multiplies, divides by standard fabric width, and adds 30 cm per drop for hems — the exact calculation workrooms use.

Curtain fabric confuses buyers because a 200 cm window never needs 200 cm of fabric: gathered curtains need one and a half to two and a half times the track width to hang with proper folds. This calculator applies that fullness multiplier, divides the gathered width by your fabric bolt width to get the number of panels, and adds 30 cm to each drop for hems. It is the same arithmetic a workroom uses before quoting, and it suits sewists, renters ordering made-to-measure curtains and anyone checking a shop's fabric recommendation.

Measure carefully before you start: the width that matters is the track or pole, not the glass, and the drop runs from the top of the track to where you want the curtain to finish, whether that is the sill, below it or the floor. Choose 1.5x fullness for light, casual curtains, 2x for the standard gathered look and 2.5x for a luxurious stack. The 30 cm hem allowance is fixed, and pattern repeats are not included, so patterned fabrics need extra length per repeat on top of the result. Two numbers decide every curtain: the finished width and the drop. The width rule — multiply track length by a fullness factor — exists because flat fabric looks like a sheet; 2× is the standard gathered look, 1.5× suits eyelets and wave headings, 2.5× gives the deep folds of luxury drapery. The drop is measured from the track (or ring eyelet, depending on heading type) to the finish point: sill level minus 1 cm, below-sill minus 15 cm, or floor length minus 1–2 cm. Then the curtain fabric calculator converts those into bolt reality: how many widths of your 140 cm (or other) fabric need joining into panels, and total metres to buy — always in one batch, because dye lots shift between rolls and a later-matched metre reads as a different colour in daylight. Patterned fabric needs an extra vertical repeat per panel join; the tool's guidance line covers that before you cut.

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