Curtain Size Calculator: What Size Curtains Do I Need?

Not sure what size curtains you need? This free curtain size calculator works out the pole or track length, the curtain drop, the width of each curtain and the ready-made size to buy, from four simple window measurements.

It works in centimetres or inches and gives UK ready-made pairs (like 66 x 90 in) or US panel sizes (like 84 or 96 in). Typical values are filled in, so change them to match your window and the results update as you type.

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How to Measure for Curtains

You only need a tape measure and four numbers. Measure in two or three places and use the largest figure, because walls and floors are rarely perfectly straight.

1. Window width. Measure the outside of the frame, or the inside of the recess if the curtains will hang inside it.
2. Window height. From the top of the frame to the sill.
3. Space above. From the top of the frame to the ceiling, so you know how high the pole can go.
4. Sill to floor. Needed for below-sill and floor-length curtains.

For the pole, Dunelm suggests adding about 20 cm (8 in) to each side of the window, and The Home Depot suggests 8 to 10 inches on each side for an outside-mount rod, so open curtains stack beside the glass instead of blocking the light. Measure the pole without its finials.

Where Should Curtains End?

The drop is measured from the top of the pole for eyelet curtains, or from the eye of the ring or the top of the track for pencil pleat curtains. Dunelm gives these finishing points:

How Much Fullness Do You Need?

Fullness is how much wider the curtains are than the pole, so they gather into soft folds when closed. Dunelm describes standard fullness as twice the pole width and a luxury look as 2.5 times, and The Home Depot suggests curtain widths of at least two to three times the rod length.

UK Ready-Made Curtain Sizes

In the UK, ready-made curtains are sold in pairs, and the size refers to each individual curtain, as Dunelm explains. The first number is the width of one curtain and the second is the drop, so a 66 x 90 in pair has two curtains, each 66 in (168 cm) wide and 90 in (229 cm) long. For standard fullness, choose a width at least as wide as your pole.

Common ready-made drops are 54 in (137 cm), 72 in (183 cm) and 90 in (229 cm), with 108 in (274 cm) in some ranges. If your drop falls between two sizes, choose the longer one and hem it, or move the pole slightly, which the calculator does for you.

US Curtain Panel Sizes

In the US, curtains are usually sold as single panels. The Home Depot lists standard lengths of 63, 84, 96, 108 and 120 inches, and many panels are about 50 to 54 inches wide. Count how many panels you need to reach your fullness, and pick the length closest to your drop.

Curtains are not only for windows: a ceiling track and floor-length panels can split a studio or hide a bed. See our room divider ideas for how to size and hang a curtain divider.

Curtain Size FAQ

Are curtain sizes per curtain or for the pair?

In the UK, ready-made sizes refer to each curtain, and curtains are sold in pairs, so a 66 x 72 in pair is two curtains, each 66 in wide. In the US, most curtains are sold as single panels, and the width on the label is the width of one panel.

What size are 66 x 54 curtains in cm?

A 66 x 54 in curtain is about 168 cm wide and 137 cm long. In a pair, each of the two curtains is that size, which suits a pole up to about 168 cm wide with sill-length curtains on a smaller window.

If my window is 180 cm wide, what size curtains do I need?

Add about 20 cm each side for the pole, which gives a 220 cm pole. For standard fullness, each curtain should be at least as wide as the pole, so a 90 in (228 cm) wide ready-made pair is the closest fit. Then choose the drop from the top of the pole to the sill or floor.

Should curtain poles be wider than the window?

Yes. A pole that extends past the frame lets open curtains sit beside the glass instead of covering it, so the room gets more light and the window looks bigger. About 20 cm (8 in) on each side is a common rule of thumb.

How high above the window should a curtain pole go?

There is no single rule. A pole a few centimetres above the frame works on most windows, and mounting it higher, closer to the ceiling, makes the window and ceiling look taller. Floor-length curtains then need a longer drop, which the calculator works out for you.

More Guides for Small Rooms

Working on a whole room? See our small bedroom storage ideas, the shelf spacing calculator for wall shelves, the rug size calculator for the floor, our washer and dryer space calculator and our storage ideas for small spaces.

How this tool was made: built with the help of AI tools, tested in the browser and published by Mohamed Elber. Results are planning estimates based on common measuring guides from curtain retailers; ready-made sizes vary by shop, so always check the label. See our Editorial Policy.