Guide to Custom Blind Sizing for a Better Fit

A blind that is a few millimetres out can look wrong every time you walk into the room. Too narrow and you get light gaps. Too wide and the blind can catch, sit awkwardly or simply not fit at all. That is why this guide to custom blind sizing starts with the part that matters most - getting clear, accurate measurements before you order.

Made-to-measure blinds are meant to solve problems, not create them. Whether you are replacing tired vertical slats in a rental, fitting blackout roller blinds in a bedroom, or sorting a wipe-clean option for a bathroom, the right size makes all the difference to how the blind looks and works day to day.

Why custom blind sizing matters

Off-the-shelf blinds can work for standard windows, but plenty of homes do not have perfectly standard recesses. Older properties, extensions and replacement windows often vary more than people expect. A custom size gives you a cleaner fit and better light control, and it usually saves the hassle of trying to make a ready-made blind work where it clearly does not.

It also helps you get the best from the product itself. Blackout blinds perform better when sized properly. Vertical blinds hang more neatly when the track width is right. Waterproof blinds in kitchens and bathrooms look tidier when they are cut to the exact opening instead of being made to do a close-enough job.

Guide to custom blind sizing: recess or exact fit?

Before measuring anything, decide how the blind will sit. This is the point where most sizing mistakes start.

Recess fit

A recess fit means the blind sits inside the window recess. This is the cleaner, built-in look that many people want in living rooms, bedrooms and kitchens. It works well when the recess is deep enough and there are no handles, vents or tiles getting in the way.

When measuring for a recess fit, you measure the width and drop of the inside of the recess. Take the measurements in millimetres. Width should be measured at the top, middle and bottom, and drop should be measured on the left, centre and right. Use the smallest width and the smallest drop so the blind has room to operate properly.

Do not make your own deductions unless the seller specifically asks you to. With made-to-measure blinds, the supplier will normally allow for fitting clearance where needed.

Exact fit

An exact fit means the blind sits outside the recess, covering the window opening. This is often the better choice if the recess is shallow, the window opens inward, or you want to reduce light gaps as much as possible. It is also useful when the recess is not square or when there are obstructions inside it.

For an exact fit, measure the area you want the blind to cover, not just the glass or frame. Many people add extra width and drop so the blind overlaps the opening. How much overlap you need depends on the window, the blind type and how much light control you want. In a bedroom, a bit more overlap usually makes sense. In a kitchen or bathroom, the neatest practical coverage is often enough.

How to measure properly

There is nothing complicated here, but there is a right way to do it.

Use a metal tape measure rather than a fabric one. Measure in millimetres only. Do not round up or down to the nearest centimetre, as small differences matter with custom products. Always measure the actual window area rather than copying old blind sizes from memory or from a rough note on your phone.

If you are replacing an existing blind, do not assume the current size is correct. Plenty of blinds are living proof of someone guessing five years ago. Measure the window again from scratch.

A pencil, paper and a second check can save you time and money. Label each window clearly if you are ordering more than one blind, especially if rooms have similar-sized windows that are not quite identical.

Measuring by blind type

Different blinds need slightly different thinking. The window size still matters most, but how the blind operates affects the final fit.

Roller blinds

Roller blinds are one of the simplest options to measure for, but you still need to think about brackets, chain controls and window handles. For recess fitting, check the recess depth and make sure the blind can roll freely without catching the handle. For exact fitting, allow enough width to cover the opening properly and reduce side light.

This matters most with blackout roller blinds. Even with a custom size, some light can show at the edges because of the operating mechanism. If maximum darkness is the goal, a slightly wider outside fit often works better than fitting inside the recess.

Vertical blinds

Vertical blinds are practical for wide windows, patio doors and rental refreshes because they are easy to maintain and easy to update with replacement slats. The key measurement is the track width and the full drop. Measure the complete span you want covered and check for skirting boards, radiators or door handles that might affect how the slats hang.

If you are only replacing slats rather than the full blind, measure the existing slat width and drop carefully. This is one area where guessing does not pay off. A few millimetres out and the finished blind can look uneven.

Waterproof PVC blinds

PVC blinds are a sensible choice in bathrooms and kitchens because they are wipe-clean and handle moisture better than many fabric options. The measuring basics stay the same, but it is worth checking for awkward tile edges, extractor vents and windows that open inward over the sink or bath. In tight spaces, an exact fit can sometimes be more practical than forcing a recess fit that leaves little room for movement.

Common blind sizing mistakes

Most errors come down to rushing. People measure once, round a number, forget about a handle, or mix up width and drop. That is all it takes.

Another common issue is measuring the glass only. The blind is not fixing to the glass, so those numbers are rarely enough. You need the full recess or the full area to be covered.

There is also the question of old houses. If a recess is out of square, the top width may not match the bottom width. That is exactly why three measurements are better than one. The smallest measurement gives you a safer working size.

For bay windows or very wide spans, it can depend on the blind style and how you want the finished look to work. In these cases, practical fit matters more than trying to force one rule onto every window.

What to check before you order

Once your measurements are written down, pause before buying. Check whether you selected recess fit or exact fit correctly. Make sure the width and drop are not reversed. Confirm the room use matches the blind type. A blackout option makes sense in a bedroom, while a waterproof, wipe-clean finish is often the better buy for steamy rooms and busy kitchens.

It is also worth thinking about how often the blind will be used. In a landlord property or family home, practicality usually comes first. Durable materials, simple operation and easy cleaning can matter more than chasing a very specific look.

If you are ordering samples, use them to narrow down colour and finish, but do not let style distract from size. A great fabric in the wrong measurement is still the wrong blind.

When custom sizing is worth it

If your window is unusual, your room needs proper light control, or you are tired of near enough never looking quite right, custom sizing is usually the better option. It gives you a blind that fits the window you actually have, rather than the one a ready-made range assumes you have.

That is especially useful when replacing parts instead of starting again. A new set of correctly sized vertical slats or a made-to-measure blind for one problem window can freshen a room without the cost of a full overhaul. For practical shoppers, that balance of fit, function and value is hard to beat.

Queen Blinds keeps the process straightforward because it should be. Measure carefully, choose the right fit, and match the blind to the room. Get those basics right and ordering online becomes much easier.

A good blind should do its job quietly every day - fit well, look neat and make the room work better. Start with the measurements, and the rest tends to follow.