Quick Answer

Blackout roller blinds are good for reducing light and glare at the window, but they usually allow light to leak around the top and sides.

Properly fitted blackout curtains usually make a bay window room darker overall because they can cover the window, the sill area, the sides of the bay and the lower part of the opening more completely.

For many homes, blackout roller blinds are enough. But if you want the room as dark as possible, well-fitted blackout curtains are usually the better solution.

How Dark Do You Really Want the Room?

This is the most important question.

If you simply want to reduce glare, soften bright daylight, or make the room darker for everyday use, blackout roller blinds may work perfectly well.

If you want the room as dark as possible for sleeping, shift work, young children, or strong early morning sunlight, blackout curtains are usually the stronger option when fitted correctly.

It is also worth being realistic. A bedroom does not always need to be completely pitch black to work well. A tiny amount of light can help you safely make out the outline of furniture if you need to get up during the night.

Where Blackout Roller Blinds Work Well

Blackout roller blinds can be a neat and practical choice, especially on straightforward windows.

They sit close to the glass, reduce direct light, and can make the room feel noticeably darker. They are also a popular first choice because they look simple and do not take up much room.

In many rooms, that level of darkness is enough.

Why Blackout Roller Blinds Still Let Light In

Roller blinds naturally leave gaps around the edges. Depending on the blind and how it is fitted, you may have light gaps at the top and both sides of the blind.

In some cases, those gaps can be around 3cm to 5cm on each side. That may not sound like much, but in a bright bedroom it can allow a surprising amount of light into the room.

This does not mean blackout roller blinds do not work. It simply means they do not usually seal a bay window as completely as well-fitted blackout curtains.

Multiple Blinds Mean Multiple Light Gaps

Bay windows often need more than one roller blind.

For example, a curved bay with five window sections may need five separate blackout roller blinds. Each blind can reduce light at its own window, but each one also creates its own top and side gaps.

This means the more blinds you have in the bay, the more possible light leakage points you create.

There is also the everyday practicality to consider. With curtains, you usually open and close one pair of curtains. With roller blinds, you may need to raise or lower several blinds individually.

Blind Chains and Child Safety

Modern roller blind chain loops need to comply with child safety requirements.

This usually means the chain loop must finish 150cm up from the floor and be secured with a safety device. In bay windows with several blinds, that can mean several chain retainers fitted around the bay.

Depending on the blind position, these retainers may need to be fixed to the wall or window frame. In some homes, this can mean screwing into uPVC frames, which not everyone wants to do.

Why Blackout Curtains Can Make the Room Darker

Blackout curtains work differently from roller blinds.

Instead of trying to block light at each individual pane of glass, the curtains cover the whole bay area more broadly. When planned properly, they can reduce light at the top, sides, centre join and lower part of the window area.

This is why properly fitted blackout curtains can often make the room just as dark, or darker, than using blackout roller blinds and curtains together.

Read our full guide to blackout curtains for bay windows

Why a Small Top Gap Is Usually Acceptable

With a ceiling fixed bay window curtain track, the curtains can sit very close to the ceiling. This helps reduce the light gap above the curtains.

Even with a very good setup, you may still see a very narrow trace of light at the top. Technically, that means the room is not in total blackout.

In real life, a tiny amount of remaining light can actually be useful. If you need to get up during the night, check on a child, or move around the room safely, a slight trace of light can help you make out vague outlines without turning a light on.

Do You Need Blackout Blinds and Blackout Curtains Together?

You can use blackout roller blinds and blackout curtains together, and in some rooms that may be the preferred choice.

However, in many bay windows, both are not necessary. Properly fitted blackout curtains can often provide an excellent level of darkness on their own.

The key is making sure the curtain track position, returns, curtain length and overlap are planned properly from the start.

So Which Option Should You Choose?

If you want a neat way to reduce light and glare, blackout roller blinds can work well.

If your main goal is to make the room as dark as possible, especially in a bay window, properly fitted blackout curtains are usually the stronger choice.

If you already have blackout roller blinds and still find the room too bright, adding well-fitted blackout curtains may solve the problem more effectively than trying to improve the blinds themselves.