Do I measure the window or the pole?

The pole, every time. Curtains are made to the track or pole, and it wants to run 15 to 20cm past the reveal on each side so the stack clears the glass.

What is curtain fullness?

Fullness is how much flat fabric is gathered into the finished width. A pencil pleat needs 2.5 times the pole width, pinch and goblet pleats 2.2, wave and eyelet around 2. Below 2 times a curtain looks skimped the moment it is drawn.

How much fabric do I need for curtains?

For a 180cm pole with a 230cm drop in pencil pleat, allow roughly 10 metres of 137cm fabric — four widths at about 2.6m cut length each. A wave heading on the same window drops to three widths.

How do I measure the drop?

From the eye of the curtain ring, or the top of a track, down to your finish point. Measure at both ends and in the middle — floors and ceilings are rarely level, and you cut to the shortest.

Should curtains touch the floor?

Floor length should clear by about 1cm so the hem does not scuff or catch. Puddled curtains add 15 to 20cm and suit bedrooms and formal rooms, but they collect dust and are wrong beside a door that swings.

The finished drop plus the heading allowance and the hem — 25 to 35cm on top, usually. It is the length actually cut from the roll, so it is what your metreage is based on.

How does a pattern repeat affect curtain fabric?

Every cut length has to start at the same point in the design, so each drop is rounded up to a whole repeat. A 64cm repeat can add half a metre per width, which on four widths is two extra metres of fabric.

How wide is curtain fabric?

Most of it runs 137 to 140cm. Extra-wide cloth at 280cm can be turned on its side, which removes the seams altogether on a standard drop.

Do I need to line my curtains?

Lining protects the face fabric from sunlight, improves the way the curtain hangs and cuts draughts; interlining adds weight and insulation again. Sheers and casual linens are the usual exceptions.

How many widths of fabric per curtain?

Divide the flat width your heading needs by the usable fabric width, then round up and keep the total even so both curtains match. Most domestic windows come out at one and a half to three widths per curtain.

Stack-back is how much pole each curtain covers when fully open — roughly a fifth of its flat width. It is the reason a pole should extend past the window: without the extension the stack sits over the glass and steals daylight.

Are eyelet curtains cheaper on fabric?

A little. They work at about 2 times fullness against 2.5 for a pencil pleat, which often saves a width. They need a pole rather than a track, and they cannot be corded.

How much does it cost to make curtains?

Fabric is usually the larger half of the bill. Making up is charged per width, typically £30 to £60 a width for hand-finished work, plus lining. The width count above is the number you will be quoted against.

Can I use this for a bay window?

Yes — measure each straight run of the bay separately and treat it as its own window, then add the results. A continuous bay pole needs a curtain per section so the fabric can pass the corner brackets.

Should curtains be wider than the window?

The pole should be, by 15 to 20cm each side. That gives the stack somewhere to go, makes the window read larger, and stops light leaking down the edges.

Curtain Calculator

How much fabric do you need?

1Your window

Units

The window

Pole or track widthcmPole to floorcm

Where should they finish?

A pair or one curtain?

Measure the pole, not the window — and if the pole is not up yet, allow 15 to 20cm past the reveal on each side for the curtains to stack.

2Your curtains

Fabric widthcmPattern repeatcm

Where do I find this?

Heading

Pencil pleat gathers at 2.5 times the pole width, with a 10cm heading allowance at the top.

Lining

Fabric price£ / mMaking up£ / width

Estimates only — confirm the fabric width and pattern repeat on your chosen cloth, and let your curtain maker check the drop before cutting.

Measuring

How to measure for curtains

Three measurements decide everything: the pole, the drop, and how far the pole runs past the glass. Hang the pole first if you can. Guessing where it will end up is how curtains end up short.

Measure the pole, not the window

End to end, finial to finial excluded. On a track, measure the track itself.

Measure the drop from the ring

From the eye of the ring — or the top of the track — to the sill or floor.

Leave room for the stack

15 to 20cm of pole past the reveal each side, so open curtains clear the glass.

The method

How to calculate curtain fabric: the method

Curtain fabric is worked out from the pole, not the window. Multiply the pole width by the fullness your heading needs, add the returns, then divide by the usable width of your cloth.

Measure the full width of your curtain pole or track and multiply it by the fullness required for your chosen heading.
Add enough for the centre overlap and returns at each side to create your total flat width.
Divide this by the usable width of your fabric and round up to the nearest whole width — for a pair of curtains, keep this number even.
Add the heading allowance and hems to your finished drop to reach the cut length, rounding up to the pattern repeat if the fabric has one.
Multiply the cut length by the number of widths to reach the total metreage, then add a little for cutting.

Order the whole quantity in one go. Fabric is dyed in batches, and a second cut weeks later will not match the first.

Fullness is the whole game

A pencil pleat wants 2.5 times the pole width, pinch and goblet 2.2, wave and eyelet around 2. Below 2× a curtain looks skimped the moment it is drawn.
Widths come in halves

Cloth is joined in half widths, and for a pair the total has to be even so both curtains match. That is why the figure jumps rather than creeping up.
Hems and headings add up

About 15cm of hem plus the heading allowance — 8cm for a wave, 22cm for a goblet pleat. On a patterned cloth the cut length rounds up again to the repeat.

Headings

Curtain headings and what they cost you in fabric

Every heading costed against the window you entered above. Hover a row to see how it would hang.

Heading	Fullness	Notes	For your window
Pencil pleatYour heading	2.5×	Gathered tape, the British default. Works on a pole or a track, and hides an uneven wall.	10.7metres
Pinch / triple pleat	2.2×	Hand-sewn pleats in a buckram band. Formal, structured, and the most durable heading.	11.1metres
Double pleat	2×	A quieter two-fold pleat. Tailored without the bulk, and kinder on a narrow window.	11.1metres
Goblet pleat	2.2×	Cupped pleats stuffed to hold their shape. Long drops and high ceilings only.	11.2metres
Wave	2×	A continuous S-curve on its own corded track. Modern, and stacks tightly.	10.6metres
Eyelet	1.9×	Rings punched through the fabric, threaded onto a pole. The most economical heading.	8metres

Ready-made

What size ready-made curtains do you need?

Standard sizes measured against your pole and drop. A pair has to reach 1.75 times the pole width before it hangs properly.

Ready-made size	Each	Against your window	Verdict
117 cm × 137 cm	per curtain	1.3× your pole width, 91.5 cm short of your drop	Too short
117 cm × 183 cm	per curtain	1.3× your pole width, 45.5 cm short of your drop	Too short
117 cm × 229 cm	per curtain	1.3× your pole width, 0.5 cm longer than your drop	Too narrow
168 cm × 137 cm	per curtain	1.9× your pole width, 91.5 cm short of your drop	Too short
168 cm × 183 cm	per curtain	1.9× your pole width, 45.5 cm short of your drop	Too short
168 cm × 229 cm	per curtain	1.9× your pole width, 0.5 cm longer than your drop	Fits
229 cm × 183 cm	per curtain	2.5× your pole width, 45.5 cm short of your drop	Too short
229 cm × 229 cm	per curtain	2.5× your pole width, 0.5 cm longer than your drop	Fits
229 cm × 274 cm	per curtain	2.5× your pole width, 45.5 cm longer than your drop	Hem required

Which is cheaper?

Ready-made price per pair

Made to measure

£740

4 widths at 2.5× fullness, cut to your drop

Nearest Ready-made

£90

229 cm × 229 cm

2.5× fullness

Ready-made saves about £650. It holds the 2.5× fullness your heading needs, and the drop is close enough to hang as bought.

Full-length curtains drawn back from a tall window — "Skimped curtains announce themselves the moment they are drawn. Buy the fullness."

Frequently Asked Questions

Once you know the metreage, choose the cloth

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