SectionHome & DIY
Last reviewed26 July 2026
Reading time5 minutes
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What this calculator works out

This calculator multiplies your pole or track width by a fullness multiplier to give the total fabric width needed, then divides it between the number of panels.

Fullness is what makes curtains look like curtains rather than flat sheets. The multiplier is the single decision that determines both how they hang and how much fabric you buy.

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Before you order

Fullness is where the money goes

Moving from 1.5× to 2.5× fullness increases the fabric by two thirds. On expensive fabric that is a substantial difference for a change that is visible but not dramatic. Heavier fabrics also look adequately full at lower multipliers than lightweight ones do.

How this calculator works

A multiplication and a division:

Total fabric width = pole or track width × fullness multiplier
Width per panel = total ÷ number of panels

The figures are finished fabric widths, before side hems and before joining fabric widths together. Most furnishing fabric is 137 cm wide, so a panel wider than that needs joining, and the join should fall at a fold rather than in the middle of a panel.

Pattern repeats add further to the requirement, since panels must match across the pair.

Worked example: a 180 cm pole

Using the default figures — a 180 cm pole at 1.5× fullness across two panels:

135 cm sits just inside standard 137 cm fabric, so each panel comes from a single width with no joins — a useful place to land. Move to 2× fullness and each panel needs 180 cm, which means joining a half-width to every panel and buying substantially more fabric. Where the requirement falls relative to the fabric width matters as much as the multiplier itself.

Common mistakes

Frequently asked questions

How much fullness do I need?

Around 1.5× for eyelet headings, which pleat themselves and look wrong if over-gathered. 2× to 2.5× for pencil pleat and pinch pleat, where the gathering is what creates the look. Sheer and voile curtains are often 2.5× to 3× because the fabric is so light. Below 1.5× curtains hang flat and look mean when drawn.

Do ready-made curtain widths include fullness?

Almost always, and this is a persistent source of confusion. A pair sold as 168 cm wide usually means each panel measures 168 cm of fabric, giving enough fullness for a track of roughly 110 to 120 cm at pencil pleat. Check the retailer's guidance on the track width the pair is intended for rather than matching their number to yours.

What if my panel is wider than the fabric?

Fabric is joined, and where the join falls matters. A joined seam should sit at the edge of a pleat or fold so it disappears into the gather rather than running down the flat centre of a panel. Half widths are usually placed at the leading edge or the outer edge depending on the design.

Should I have one curtain or a pair?

A pair is standard and draws evenly. A single panel suits a narrow window, a door, or a room where the curtain stacks to one side to preserve a view or clear a radiator. On a wide window a single panel needs a very large stack-back and rarely looks right.

Is what I enter stored?

No. Measurements are processed in your browser and never transmitted or retained.

Related tools

Curtain Drop CalculatorThe length measurement to go with this width. Wall Fixing AdvisorFixings for a pole carrying heavy lined curtains. Room Paint PlannerThe rest of the room the curtains are going into.

References

Sources are checked at publication and can change — how I choose and check references.

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