How to Measure for Curtains: An Illustrated Guide

Williamsons · Measuring made simple

How to measure for curtains

A few careful measurements make choosing new curtains much easier. Follow this illustrated guide for ready-made eyelet and pencil pleat pairs, single door curtains and sheer voile panels.

1. Start with your pole or track

Have a metal tape measure and somewhere to write your measurements. Keep the tape straight and measure each window separately, even if they look alike. Use either centimetres or inches throughout your calculations.

Fit the pole or track before taking final measurements. A common starting position is around 10–15cm above the window, extending around 15–20cm beyond each side, where the space and fittings allow. This gives the curtains room to cover the edges and pull back from the glass. Check for handles, recesses and nearby furniture before deciding the position.

Measure the full usable length of the pole, excluding decorative finials, or the length of the track the curtains will cover. If the track includes an overlap or return, follow the track maker’s measuring instructions. For a bay window, measure along the fitted track or pole rather than straight across the bay.

2. Allow for fullness when choosing the width

Cur­tains need extra fabric to create folds when they are closed. This extra width is called fullness or gather. Buying only enough flat fabric to span the pole can leave the curtains looking stretched.

For most ready-made eyelet or pencil pleat pairs, aim for about twice the pole or track width in total flat fabric. Fuller folds may need around 2.5 times the width, depending on the fabric and heading. Check any range-specific guidance on the product page.

A worked example

For a pole measuring 160cm, double fullness needs 320cm of fabric in total: two curtains at least 160cm wide each. A 66″ (168cm) width pair provides 336cm altogether, giving approximately 2.1 times fullness. A pair marked 90″ (229cm) provides 458cm altogether, so it gives considerably fuller folds on that same pole.

Use this table as a guide to fullness, not a guarantee of fit. Available sizes vary by range, and centimetre equivalents on our size labels are rounded.

3. Measure the drop for your heading

The drop is the curtain’s length. Decide where you want the bottom hem to finish, then measure vertically from the correct starting point for your heading. Take readings at both sides and the middle to spot uneven floors or sills.

Eyelet curtains — for poles

Measure from the top of the pole to your chosen hem position. The fabric heading sits above the pole, so check how the selected range states its drop. Where the listed drop is the full fabric length from top edge to hem, include that extra heading height when comparing sizes. It is often around 3–4cm, but varies by design: do not automatically add it again if the manufacturer already allows for it.

Check that the pole fits through the eyelets and that the folds have room to move clear of the wall and window handles.

Pencil pleat curtains — for poles or tracks

On a pole, measure from the small hook eye beneath the curtain ring to your chosen hem position. On a track, use the track or hook starting point specified by its maker; the hook position on the heading tape affects how high the curtain hangs. Allow for the tape above the hook when matching your measured hanging length to the finished fabric drop.

The stated curtain width is measured before gathering. Gather each panel evenly to cover roughly half the track or pole, with enough overlap for the pair to close neatly.

4. Choose where the hem will finish

• At the sill: leave around 1cm above it so the hem does not drag.
• Below the sill: around 15cm below is a useful starting point, where the space allows.
• At the floor: around 1cm clear gives a practical finish. Use the shortest measurement if the floor is uneven.
• Near a radiator: choose a finish clear of the radiator so the curtains do not trap heat behind them. Follow the heater maker’s clearance requirements.

Compare the drop you need with the sizes available in the range. Width and drop are separate choices: moving to a longer drop does not necessarily give you a wider curtain. If no standard drop suits, ask us about the product before ordering or plan any alteration separately.

5. Measuring for a single door curtain

A door curtain is one panel rather than a pair. Measure the pole or track across the area to be covered, allowing coverage beyond the door edges where possible. Check that the door can open freely and that there is room to move the curtain aside.

Use the drop instructions above for the door curtain’s heading, and leave practical clearance above the floor. For folds, calculate the width using coverage width × chosen fullness. Do not divide by two for a single panel. For example, a 90cm span at 2× fullness needs approximately 180cm of flat fabric in one panel. Check the actual sizes and lining details on the product page.

6. Measuring for voile panels

Voiles are sheer and unlined, and our panel listings are sold individually. Measure the rod, pole or track they will cover. For a lightly gathered appearance, aim for roughly 1.5× the coverage width; for fuller gathers, aim for around 2×.

Multiply the coverage width by your chosen fullness, then divide by the flat width of one panel to find how many panels you need. Round up to a whole number. For example, a 150cm span at 2× fullness needs 300cm of voile: two 150cm-wide panels provide that amount. One pack contains one panel, so order two packs if you want two panels.

Check the heading before measuring the drop. A slot-top voile has a pocket for the rod; any decorative fabric above that pocket is part of the finished fabric length. Allow for its position on the rod and check the range’s sizing details. For eyelet or pencil pleat voiles, use the corresponding heading instructions above.

7. Reading our size labels

For a pair, each curtain has these dimensions. Two 229cm-wide panels provide approximately 458cm of flat fabric before gathering. For a door curtain or voile, the dimensions refer to the single panel. W means width; L means length or drop.

Centimetre conversions are rounded to the nearest whole centimetre (1 inch = 2.54cm). Small differences such as 228cm and 229cm can reflect rounding or manufacturer labelling; use the selected product’s stated measurements and instructions.

8. Check before you order

• I measured the fitted pole or track and excluded the finials.
• I allowed enough total fabric for the folds I want.
• I checked whether the product is a pair or a single panel.
• I measured the drop from the correct point for the heading.
• I checked sill, floor, radiator and door clearance.
• I selected the width first and the drop second, and checked the quantity.

Common questions