Thermal or blackout curtains: what is the difference and which should you choose?

When temperatures drop or evenings get darker earlier, curtains become much more than a decorative detail. They help manage privacy, light and, depending on their construction, the level of comfort you feel near windows and glazed doors.

But the terms blackout curtain, thermal curtain and light-filtering curtain are often confused. They do not describe the same function.

So should you choose a thermal or blackout curtain? Can one curtain provide both benefits? And what should you check before buying? Here is a practical guide to help you choose without relying only on colour or thickness.

Thermal and blackout curtains: the essential difference

A blackout curtain is designed mainly to block a large amount of incoming light. It is particularly useful in bedrooms, rooms exposed to street lighting or whenever you want a darker atmosphere.

A thermal curtain is primarily designed to improve comfort near windows by adding an extra textile barrier between the room and the glazed surface.

Some products may combine both functions, but that is not automatic. A thick curtain is not necessarily thermal, and a dark curtain is not automatically blackout.

What is a blackout curtain actually for?

The main purpose of a blackout curtain is to reduce the amount of light entering the room. Its effectiveness depends on the fabric construction, density and, in some cases, a special lining.

• a bedroom facing a bright street;
• a room without shutters;
• people who are sensitive to morning light;
• children’s rooms used for daytime naps;
• spaces where you want a more enveloping atmosphere.

The BJORN blackout curtain with fleece lining is clearly described as blackout. Its fleece lining also gives it a fuller drape, making it a good example of a curtain designed first of all to limit light.

What is a thermal curtain for?

A thermal curtain mainly aims to improve comfort near a window or glazed door. In winter, a cold pane can create an uncomfortable sensation even when the overall room temperature seems acceptable.

An additional textile layer can help reduce that sensation. However, it remains a complement: no curtain replaces efficient glazing, good airtightness or proper insulation.

Can a curtain be both thermal and blackout?

Yes, some models combine several functions. The important point is to read the product description carefully instead of guessing from the curtain’s appearance.

A heavy velvet curtain can look very warm without being sold as thermal. Conversely, a technically lined curtain can be effective without looking especially heavy.

Which curtain should you choose for a bedroom?

In a bedroom, darkness is often the priority. A blackout curtain is therefore usually the most logical choice if outside light bothers you.

You can then choose the material, colour and drape according to the atmosphere you want. For more ideas, our guide to creating a cosy bedroom for autumn and winter complements this topic with bed linen, cushions, throws and lighting.

Which curtain should you choose for a living room?

In a living room, complete blackout is not always necessary. The priority is often a balance between privacy, natural light and decoration.

The Elise plain curtain creates a more intimate atmosphere thanks to its substantial cotton fabric, while the Soline washed-linen curtain offers a lighter and more natural look.

What about a large window or patio door?

Large glazed surfaces require careful measuring. Width, drop and fabric volume all matter if you want the curtain to fall nicely and cover the opening properly.

For a glazed door without shutters, a blackout curtain can be particularly useful in the evening. Whatever the function, a curtain that is too narrow or too short will be much less effective.

How to measure curtains correctly

Start with the width of the curtain pole rather than only the window itself. To create attractive folds, the total fabric width should be greater than the opening.

• just above the floor for a clean, practical look;
• touching the floor for a more elegant finish;
• slightly pooling on the floor for a fuller decorative effect.

Also check the hanging system before ordering: eyelets, clip rings or another solution according to the pole already installed.

Does colour affect blackout performance?

Not on its own. A black curtain is not automatically blackout, and a light curtain can still be designed to block light effectively.

Colour mainly affects the mood of the room. Deep tones reinforce a cosy feel, while beige, ecru and natural colours keep the room brighter.

Which material should you choose?

• Cotton offers a natural and versatile look.
• Cotton velvet adds depth and a more enveloping feel.
• Washed linen gives a relaxed and natural drape.
• Polyester is often useful for technical curtains and easy-care products.

The Soline curtain is ideal for a more airy natural look, while deeper fabrics are better suited to a more cocooning mood.

Thermal or blackout curtain: choose in 30 seconds

• You want a dark bedroom: choose a curtain clearly described as blackout.
• You feel discomfort near a cold window: look for a curtain designed to improve thermal comfort and that covers the opening properly.
• You want both: choose a model explicitly combining the two functions.
• You mainly want a cosy atmosphere: focus on material, colour and drape.
• You want to keep plenty of daylight: choose a lighter or filtering curtain.

How to care for your curtains

Curtains can collect dust and household odours, particularly in winter. Always follow the care label and wash according to the material. Our care-label guide can help you understand the symbols.

Our favourite curtains

Here are four currently available models that illustrate different styles and uses.

You can also browse our full range of curtains.

FAQ: thermal or blackout curtains

Does a blackout curtain also protect from the cold?

Not necessarily. Blackout and thermal describe two different functions. Some curtains combine both, but you need to check the product description.

Which curtain is best for a bedroom?

If darkness is your priority, choose a curtain clearly described as blackout, then select the material and colour according to the atmosphere you want.

Can thermal curtains replace insulation?

No. They can improve comfort near an opening, but they do not replace efficient glazing or proper insulation.

How can you tell whether a curtain is really blackout?

Do not rely only on colour or thickness. Check that the blackout property is explicitly stated in the product description.

What curtain length should you choose?

A curtain can stop just above the floor, touch it, or pool slightly depending on the style and maintenance you prefer.