Blackout vs Blockout Curtains: Is There a Difference?

Short answer: blackout and blockout curtains are the same thing. "Blockout" is the usual word in Australia, New Zealand and parts of the UK; "blackout" is the usual word in the US and most of Europe. Both describe curtains made to stop light coming through the fabric. How dark your room actually gets depends on two things: how the fabric is built, and how well the curtain covers the window edges.

Blackout or blockout: is there a difference?

No. You will find guides claiming that blackout curtains block 95 to 99% of light while blockout curtains block 100%, but there is no industry standard behind that split. Shops in Sydney sell "blockout curtains" and shops in Chicago sell "blackout curtains", and they are the same products under two regional names.

The distinction that does exist is between blackout (or blockout) and room-darkening curtains. Room-darkening fabric cuts most of the light but lets a dim glow through. Blackout fabric is built to stop light passing through the cloth itself. When a seller says "100% blackout", they mean the fabric, not the room: light still gets in around the edges unless the curtain is hung to stop it.

How blackout fabric blocks light

There are three common ways to make a curtain block light, and they behave differently:

• Triple-weave fabric. A dense weave with a dark yarn woven through the middle. It drapes softly and looks like ordinary curtain fabric on both sides. Very light colours can still show a faint glow in strong sun.
• Coated or backed fabric. A face fabric with a light-blocking layer bonded to the back, often acrylic foam. This blocks the most light, but the back looks rubbery and the fabric is stiffer.
• A separate blackout lining. Any curtain, including linen, sewn or hooked to a blackout liner behind it. You keep the fabric you like on the room side and get the light control from the lining.

To check a curtain before you hang it, hold it up to a bright window or shine a phone torch through it. If you can see the light, so will your bedroom at six in the morning.

Why a blackout curtain still lets light in

Most complaints about blackout curtains are really complaints about gaps. Light comes in through four places:

• Above the rod, when the curtain is hung inside or just above the window frame.
• At the sides, when the panels stop at the edge of the glass.
• In the middle, where two panels meet without overlapping.
• Below the hem, when the curtain stops short of the sill or floor.

The fabric can be perfect and the room still bright if any of these are open. Fixing the gaps does more for a dark room than buying a more expensive curtain.

How to hang blackout curtains for a fully dark room

• Mount the rod or track higher and wider than the window. 10 to 15 cm above the frame and 15 to 25 cm past each side is a good starting point.
• Close the top. A ceiling-mounted track, a pelmet or a box above the rod stops the strip of light that shines over the top.
• Close the sides. Wrap-around (return) rods bring the curtain back to the wall so light cannot slip past the edge.
• Overlap in the middle. Buy enough width that the panels overlap where they meet, or use an overlap arm on a track.
• Go long. Floor-length curtains, or at least 15 to 20 cm below the sill, block the light that bounces up from below.
• Layer with a blind. A blackout roller blind inside the window recess, with curtains in front, is the most reliable way to get a room truly dark.

For width, most curtains look right at about twice the width of the rod for a gathered look. Our curtain buying guide covers measuring in more detail.

Blackout, room-darkening or sheer: which do you need?

We stock blackout and sheer panels in the same washed-linen finish — see the curtain range.

Choose by what the room is for, not by the strongest label on the shelf.

• Blackout for bedrooms, nurseries, shift workers who sleep during the day, and rooms with a projector or TV that catches glare.
• Room-darkening for rooms where you want to cut glare and heat but do not need darkness, such as a home office.
• Sheer or light-filtering for living rooms, where you want privacy and soft daylight. Natural linen on its own filters light rather than blocking it.

If you love the look of linen but need a dark bedroom, hang a linen curtain in front of a blackout lining or a blackout blind. You get the texture on the room side and the darkness behind it. Our guide to linen sheer curtains shows how to layer them.

Room-by-room recommendations

Bedrooms. Blackout fabric plus attention to the gaps. If street lights or early summer sunrises wake you, close the top and sides as well.

Nurseries and children's rooms. Blackout curtains with a blackout blind behind them make daytime naps far easier. Keep cords out of reach, or use cordless blinds.

Media rooms. Blackout curtains on every window, ideally dark colours on the room side so they do not reflect the screen.

Living rooms. Usually light-filtering or room-darkening. A sheer for the day with a heavier curtain for the evening covers both.

Home offices. Room-darkening or a blind angled to stop glare on the screen is usually enough. Full darkness makes a workroom feel closed in.

Do blackout curtains keep heat out and reduce noise?

Heavier, lined curtains help with temperature. In summer they stop the sun heating the room through the glass, and in winter a closed, lined curtain cuts the cold that comes off the window and the draughts around old frames. The effect is largest on single-glazed or poorly sealed windows, and it depends on the curtain covering the window closely, the same as for light.

For noise, thick fabric softens echo inside a room and takes the edge off some outside sound, but curtains are not soundproofing. If traffic noise is the main problem, the window itself is where to spend.

Caring for blackout curtains

• Triple-weave curtains usually wash like ordinary fabric. Check the label for temperature.
• Coated backings should not be tumble dried hot or ironed on the coated side, as heat can crack the layer.
• Separate linings can be taken off and washed apart from the face fabric, which keeps a linen curtain looking soft for longer.
• Vacuum curtains with a brush attachment every few weeks to keep dust from building up in the weave.

Summary

Blackout and blockout are two names for the same curtains. What decides how dark a room gets is the fabric construction (triple-weave, coated or lined) and how well the curtain covers the window: higher and wider than the frame, overlapping in the middle, long at the bottom, and ideally layered with a blind. Get the gaps right and a well-made blackout curtain will give you a properly dark room. See our linen and blackout curtains.

For the layered look — a sheer panel by day, a blackout panel behind it at night — browse our linen curtains and drapes.