Curtains do three jobs: they give privacy, shut out light, and keep heat in. In a British house the third matters most in winter, since a closed, lined curtain over a window at dusk is one of the simplest ways of reducing heat loss.
The choices are the heading, the lining, the length and the fullness, and each has a conventional answer. Corded tracks and blinds carry a known danger to small children, and blinds sold since 2014 have had to be supplied with a safety device.
The heading is the top of the curtain, and decides how it hangs and what it hangs from.
Width is measured along the track or pole, not across the window. The curtains together should be between one and a half and two and a half times that width, depending on the heading; the figure is called the fullness, and curtains made too narrow look mean when closed.
Length, called the drop, is measured from the top of the track, or from the underside of the pole rings, to one of three points: the sill, about 15 centimetres below it, or just clear of the floor. Anything in between looks like a mistake.
Ready-made curtains come in a small range of widths and drops, still commonly labelled in inches. Made-to-measure curtains are cut to the window.
A track is discreet and bends round a bay. A pole is meant to be seen. Either should extend beyond the window on each side, so that the open curtains stack against the wall and not across the glass, and be fixed into something solid: lined, full-length curtains are heavy.
Closing curtains at dusk keeps heat in the room, and the Energy Saving Trust lists it among its basic measures. Two details decide how well it works. A curtain that hangs in front of a radiator sends the heat up behind it to the window, so curtains above a radiator stop at the sill, or are tucked behind it. And a curtain that fits closely at the top and sides stops the cold air against the glass from spilling into the room.
Heavier fabrics hang better and insulate more. Strong sunlight fades and eventually rots unlined fabric, silk fastest. Many curtain fabrics shrink when washed, and lined curtains shrink unevenly, so the care label is followed; dry cleaning is common for anything interlined.
Looped cords and chains on blinds, and the pull cords of corded curtain tracks, can strangle a small child. The Royal Society for the Prevention of Accidents records that nine children died in this way in the United Kingdom between April 2019 and March 2022, and at least 33 in the twenty years before.
Since 2014, new blinds with looped cords or chains have had to come with a safety device, fitted or supplied. The society's advice on blind cords for existing blinds and corded tracks is: