How to Measure Windows for Exact Blinds

A blind that is 1 cm out can look wrong every single day. Too tight, and it catches on the recess. Too narrow, and light leaks through the sides. If you want to measure windows for exact blinds, the good news is that it is straightforward once you know what to check and where to measure.

The main thing is not to rush. Most measuring mistakes happen when someone takes one quick width, rounds it up, and assumes every window is square. They rarely are. A careful five-minute measure now is far easier than dealing with a blind that does not sit properly later.

Before you measure windows for exact blinds

Start with a steel tape measure, not a cloth sewing tape. A steel tape stays straight and gives a more reliable reading, especially across wider windows. You will also want a pencil, paper, and somewhere to note each window clearly by room.

Measure in millimetres rather than centimetres. It avoids confusion and gives a more exact size for made-to-measure blinds. Do not round up or down unless the product instructions specifically tell you to. For custom blinds, exact figures matter.

It also helps to decide first whether you want an inside recess fit or an outside exact fit. That choice changes how you measure.

Recess fit or exact fit?

A recess fit means the blind sits inside the window recess. This usually gives a neat, built-in look and keeps the sill clear. It is a popular choice for roller blinds and vertical blinds where there is enough depth inside the recess.

An exact fit, sometimes called face fit, means the blind is fixed outside the recess, onto the wall or frame. This can be the better option if the recess is shallow, the window opens inward awkwardly, or you want to block more light around the edges.

Neither option is automatically better. It depends on the window, the room, and what matters most to you - a tidy in-recess finish, better blackout coverage, or practical clearance for handles and vents.

How to measure for recess blinds

If you are fitting the blind inside the recess, measure the width in three places - top, middle, and bottom. Then measure the drop in three places - left, centre, and right. Use the smallest width and the smallest drop.

This matters because very few window recesses are perfectly even. If you only measure once at the top and order to that size, the blind may not fit lower down. Using the smallest measurement gives the blind the best chance of sitting properly within the space.

Check the recess depth too. This is often missed. Some blinds need more room than others, especially if you have handles that stick out or tiles around the window in kitchens and bathrooms. If there is not enough depth, an outside fit may be the simpler option.

When ordering recess blinds, always follow the measuring guidance for that blind type. In many cases, you provide the full recess size and the manufacturer makes the allowance for fitting. That is why you should not take deductions unless told to do so. Guessing the allowance yourself is one of the most common mistakes.

A note on window handles and obstructions

Handles, trickle vents, alarm sensors and tiles can all affect how a blind sits. If your handle projects into the recess, measure from the point that matters most for clearance, not just the plaster line. A blind may technically fit the recess width but still rub every time the window opens.

For blackout blinds, this matters even more. If you want better light control in a bedroom, an outside fit can sometimes work better than a recess fit because it covers more of the window edges.

How to measure windows for exact blinds outside the recess

For an outside fit, you are deciding how much coverage you want, so there is a little more flexibility. Measure the width and drop of the area you want the blind to cover, not just the glass.

A practical rule is to allow overlap beyond the window opening so the blind covers the edges properly. This can help with privacy and reduce light gaps. How much overlap you choose depends on the wall space available, nearby fittings, and the style of blind.

If the window sits close to a side wall, cupboard, or another obstacle, you may not be able to add the same amount on both sides. In that case, work with the space you have. The blind does not need perfect symmetry if the room layout does not allow it, but you do want enough coverage to look intentional.

When measuring the drop, think about where the blind will start and finish. You may want it to sit just below the sill, cover the full recess, or extend further for a fuller look. In bathrooms and kitchens, check for radiators, taps, or tiled areas that could affect where the blind hangs.

Measuring by blind type

Different blinds have slightly different practical considerations, even if the measuring method is broadly similar.

Roller blinds

Roller blinds are usually the most straightforward to measure. For recess fitting, take the smallest width and drop across three points. For exact fitting, measure the coverage area you want. If blackout is the priority, a face fit often reduces side light better than a recess fit.

Vertical blinds

Vertical blinds work well for wide windows and patio doors, but top fixing space and stack position matter. Make sure there is enough room for the headrail and think about how the slats will draw back. If you are replacing an old vertical blind, it is worth checking whether you need a full new blind or simply replacement slats.

PVC waterproof blinds

In kitchens and bathrooms, wipe-clean PVC blinds are a practical choice, but measuring still needs care. Moisture is not the problem here - awkward recesses often are. Tiled reveals, shallow depths, and window handles can all affect whether a recess fit is realistic.

Common measuring mistakes that cost time

The biggest mistake is measuring only once. The second is using rounded numbers. The third is assuming every product is measured the same way.

Another regular issue is confusing blind size with fabric size. On some blinds, the overall blind width includes brackets or controls, while the fabric itself is slightly narrower. That is normal, but it can surprise people if they expected edge-to-edge coverage. If privacy or blackout matters, that detail is worth checking before you order.

People also forget to label their measurements properly. If you are ordering more than one blind, write down each room and each window clearly. “Bedroom front”, “kitchen small window”, and “bathroom side” is much better than three widths on a scrap of paper that all look the same later.

When it is worth measuring twice

If the window is bay-fronted, noticeably uneven, or in an older property, double checking is time well spent. Older homes often have recesses that look straight at a glance but vary enough to matter for made-to-measure blinds.

It is also worth rechecking if you are ordering several blinds together. A full set of custom blinds can transform a room, but only when each one fits as intended. Taking a second set of measurements helps avoid one odd blind spoiling the finish.

For landlords and property refreshes, accurate measuring is especially useful because it keeps replacement simple. If a worn blind or damaged slat needs updating later, having the right dimensions on file saves time and avoids buying a full new setup when only one part needs changing.

Measuring for exact blinds without overthinking it

You do not need specialist tools or an in-home appointment to get this right. You just need the correct fit type, a steel tape, and a careful approach. Measure width and drop in three places for recess blinds, use the smallest figures, and check depth before ordering. For outside fitting, measure the area you want to cover and allow for practical overlap.

If you are buying made-to-measure blinds from a retailer like Queen Blinds, the point is simple - custom sizing only works properly when the starting measurements are right. Get those right, and the rest is easy.

Take your time, write every figure down in millimetres, and trust the tape measure rather than guesswork. A well-fitted blind does not shout for attention, but you notice the difference every day.