Curtains can change a room, but only if the measurements are right. A pair that skims the floor and closes with a generous overlap looks considered; one that hangs short or leaves a bright gap at the edge feels like a near miss. Measuring is not complicated. It needs a little patience, a metal tape and a decision or two about how you want the curtains to work before you start writing numbers down.

Decide how the curtains will hang before you measure

The same window can take a wall-mounted pole, a ceiling track or a recessed track, and each choice changes the width and drop. Stand back and decide: outside the recess for a fuller, more generous look, or inside the recess to keep the window area neat? A pole above the frame? A track fixed to the ceiling? Floor-length, sill-length or just below the sill? Mark the intended position lightly with pencil or painter’s tape, then measure from that line—not from the glass.

If you are replacing existing curtains, measure the track or pole, not the old curtains. Old curtains may have been made with a different fullness or hem, and copying them can repeat a mistake.

The four numbers to record at every window

1. Track or pole width: the full width the curtains will cover, including any overlap in the middle.
2. Finished drop: from the point where the curtain hangs—the underside of a ring or glider, or the hanging point your supplier specifies—to the desired hem.
3. Stacking space: how much wall each curtain needs when open. As a guide, allow roughly one-quarter to one-third of the track width per side, depending on fabric and heading.
4. Obstructions: radiators, sills, handles, sockets, furniture and door swings.

Write everything in centimetres and keep the same unit throughout. Sketch each window with the numbers on it; it is easier to spot a missing measurement on paper than in a shop.

Standard windows: the basic checklist

Most standard windows are straightforward, but small differences in the recess matter. Measure the width in three places—top, middle and bottom—and use the smallest figure if the curtains are going inside the recess. Walls are rarely perfectly square.

If the curtains hang outside the recess

• Measure the width of the track or pole, not the window. As a rule, extend it 15–20 cm beyond each side of the recess so the curtains can stack clear of the glass.
• Check that the pole or track has a wall fixing at each end and, for wide spans, in the middle.
• Measure the drop from the hanging point to the floor, sill or radiator top. For floor-length curtains, subtract 1–2 cm so the hem just clears the floor.
• Note the return to the wall: curtains need enough fabric to wrap back without pulling.

If the curtains hang inside the recess

• Measure the recess width at the top, middle and bottom; use the smallest figure.
• Measure the recess depth. A bulky heading needs more room than a slim track.
• Measure the drop from the track to the sill. If you want the curtains to sit on the sill, allow a small clearance; if below, decide by how much.
• Check for tiles, trim or uneven plaster that could stop the curtains hanging straight.

For a pair of curtains, add 5–10 cm of overlap in the middle if you want them to close without a gap. Tell your curtain maker or supplier whether the width you are giving is the track width or the finished curtain width—they are not the same thing.

Wide windows and multi-pane spans

A wide window—a living-room slider, a bank of three panes, a garden-facing span—needs a different kind of attention. One very wide pair can work, but two pairs on a shared track often stack more neatly and are easier to handle.

• Measure the full span you want to cover, then decide whether you want one pair or two. For two pairs, mark the centre point and measure each half separately.
• Check where the track or pole will be fixed. Long tracks need intermediate brackets; make sure they do not clash with window frames or curtain rings.
• Record the stacking space at each side. A heavy fabric may need more wall space than you expect when the curtains are open.
• Look for radiators, low sills and furniture. A sofa or bench under the window can change the drop you choose.
• If the window has sliding panes, note which side opens. You may want the curtains to stack away from the opening.

A simple sketch with the total width, the centre mark and the drop at each end will save confusion. If the floor slopes or the ceiling line is uneven, measure the drop at both ends and in the middle, then use the shortest measurement for a floor-length curtain.

Balcony doors and French doors

Balcony doors need curtains that can move with the door and still look generous when closed. The measurements are similar, but the details matter more.

• Measure the full height from the track or pole to the floor. For doors that open inwards, check that the curtain will not catch on the handle, the door frame or the floor.
• Measure the width of the whole door plus frame, then add 15–20 cm on each side if you want the curtains to stack clear of the glass and door.
• Note the door swing and handle position. A curtain that covers the handle can be awkward; a tieback or a shorter drop may help.
• If there is a radiator below the window or beside the door, decide whether the curtain should finish above it or hang behind it. Never block a radiator if you want the room to heat properly.
• For French doors, measure each leaf separately and check that the curtains do not interfere with the opening. A track that extends beyond the frame gives the curtains somewhere to go.

For balcony doors, floor-length curtains usually look best, but allow 1–2 cm of clearance so the hem does not brush the floor. If the door opens inwards, stand in the doorway and watch the curtain as you open the door—better to find the clash now than after the curtains are made.

Room-by-room adjustments that change the numbers

• Living room: measure for the way you use the room. If you close the curtains in the evening, check the overlap and the drop behind the sofa.
• Bedroom: blackout curtains need enough width to overlap and enough drop to cover the top of the window. Measure from the track, not from a decorative pole if the pole is only for show.
• Kitchen: shorter curtains may be more practical. Check the space above worktops and avoid a hem that sits where it will be splashed.
• Bathroom: measure the recess and check for

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