Custom Roller Blind Sizes Explained

A roller blind that is 10 mm too narrow does not look “nearly right”. It looks wrong every time you open the curtains, and it usually lets in more light than you expected. That is why custom roller blind sizes matter. They take the guesswork out of buying blinds online and give you a finish that suits the window, the room and the way you actually use the space.

Off-the-shelf sizes can work for some windows, but plenty of homes do not have standard recesses. Older properties, extensions, bay windows and replacement windows often vary more than people think. Even in newer homes, one side of the recess can be slightly tighter than the other. Made-to-measure sizing is not about making things fancy. It is about getting a blind that fits properly, hangs neatly and does the job you bought it for.

Why custom roller blind sizes make a difference

The main difference is fit, but fit affects more than appearance. A well-sized roller blind gives better privacy, better light control and a cleaner line across the window. If you are buying blackout fabric for a bedroom, size matters even more. Gaps at the sides can let in enough light to make the blind less effective, especially in summer when mornings start early.

There is also the day-to-day practical side. A blind that is too wide can catch in the recess or sit awkwardly against handles and trims. One that is too short can leave the lower part of the window exposed. A proper made-to-measure blind avoids those problems and saves the hassle of trying to make a standard size work.

For landlords and anyone updating a room on a budget, custom sizing can also be the more sensible buy. Replacing a tired blind with one that fits the existing window properly often looks like a bigger upgrade than spending more on a poor-fitting alternative.

Recess fit or exact fit?

Before you think about numbers, you need to decide how you want the blind to sit. Most roller blinds are ordered either as a recess fit or an exact fit.

Recess fit

A recess fit means the blind sits inside the window recess. This gives a tidy, built-in look and is a popular choice for kitchens, bathrooms and living rooms. It works best when the recess is deep enough for the blind and there are no obstructions such as handles, vents or tiles that project into the space.

When ordering for a recess fit, you usually measure the width and drop of the recess itself. Manufacturers will often make the small deductions needed so the blind can operate properly within that space. That is why it is always worth checking whether the size you enter is the recess size or the finished blind size.

Exact fit

An exact fit means the blind is made to the precise size you give and is usually fitted outside the recess. This is useful when the recess is too shallow, the window has protruding handles, or you want better coverage to reduce side gaps. It can also make a small window look a bit larger because the blind covers more wall area around it.

There is no universal best option. A recess fit looks neat and contained. An exact fit can offer stronger blackout performance and cover awkward openings more effectively. It depends on the room, the window and what matters most to you.

How to measure for custom roller blind sizes

Measuring is not difficult, but it does need care. A steel tape measure is best because fabric tape can flex and throw you off. Measure in millimetres rather than centimetres if possible. It is more precise and helps avoid rounding errors.

Measuring a recess fit

Take the width measurement in three places - top, middle and bottom. Then use the smallest width. Recesses are often not perfectly square, even when they look fine at first glance.

For the drop, measure the left side, centre and right side, then use the largest drop. This makes sure the blind is long enough to cover the full window opening.

If there are tiles, window handles or other fixtures, measure with those in mind. A blind that fits the recess on paper may not operate well if something projects into its path.

Measuring an exact fit

Measure the area you want the blind to cover, not just the glass. If you want stronger light control, add extra width beyond the edges of the window or recess where possible. The same applies to the drop if you want the blind to sit slightly above and below the visible window area.

This is where room use matters. For a bathroom or kitchen, you may want a practical fit that avoids hitting sills, taps or surrounding surfaces. For a bedroom blackout blind, you may want wider coverage to limit light bleed.

What affects the finished size?

One point that often catches people out is that the fabric width is usually narrower than the full blind width. That is because the overall width includes the operating mechanism and brackets. So if you are expecting the fabric itself to run exactly wall to wall, it may not.

This is normal for roller blinds, but it is worth keeping in mind if privacy or blackout is a priority. In those cases, a slightly wider exact fit can make a real difference.

The chain side and bracket placement can also affect how the blind sits, particularly in tight recesses. If you have limited space or obstacles near one side of the window, it helps to think ahead about where the controls will go and whether there is enough clearance.

Choosing the right blind size for different rooms

Custom roller blind sizes are not just about matching the opening. They should also suit the room.

Bedrooms

For bedrooms, light control is usually the main concern. Blackout blinds work best when the sizing reduces side gaps as much as possible. If the recess is narrow or uneven, an exact fit outside the recess may give better results than fitting inside it.

Bathrooms and kitchens

In bathrooms and kitchens, practicality matters most. Moisture-resistant and wipe-clean materials are often the better option, but sizing still matters. You need enough coverage for privacy without the blind interfering with handles, splashbacks or tiled reveals.

Living rooms and dining rooms

In main living spaces, appearance often carries more weight. A recess fit can look smart and understated, especially if you want the blind to sit behind curtains. If the blind is the main window covering, a slightly broader exact fit can look more finished.

Rental properties

For rental homes, durability and speed matter. Custom sizing helps because it reduces returns, trimming, bodged fittings and the general wear that comes from an ill-fitting blind being pulled and adjusted every day. A proper fit tends to last better because it operates as intended.

Common mistakes to avoid

The biggest mistake is guessing. Measuring “roughly” and hoping for the best usually costs more in the long run. The second is mixing up recess size with blind size. If a retailer asks for recess measurements and you submit a reduced finished size, the blind may arrive too small.

Another common issue is forgetting obstructions. Window handles are the usual culprit, but tiles, alarm sensors and deep sills can matter too. A blind can be accurately made and still be wrong for the space if those details are missed.

It is also worth ordering with the room’s use in mind rather than just the window shape. A neat blind inside the recess may look great in a photo, but if it leaves too much morning light in a child’s bedroom, it is not the right choice.

Are custom sizes worth it?

For most people, yes. Not because every window needs something complicated, but because a blind is only as good as its fit. If you are already choosing the fabric, colour and finish you want, getting the size right is the part that makes the whole thing work.

Custom sizing does not have to mean expensive or difficult. It simply means ordering a blind built around your measurements instead of trying to force your window into a standard bracket. That is especially useful if you want blackout performance, waterproof materials, a particular look, or a straightforward replacement without the usual back-and-forth.

Queen Blinds focuses on that practical side of made-to-measure. The point is not to make ordering feel technical. It is to make sure the blind arrives ready to hang and suited to the window it is meant for.

If you take a few extra minutes to measure properly, you give yourself a far better chance of getting a blind that looks right, works properly and keeps doing its job long after fitting day.