How to Measure for Interior Window Shutters

A few millimetres can be the difference between shutters that look as though they belong to the room and shutters that feel like an afterthought. Knowing how to measure for interior window shutters gives you a useful starting point, whether you are planning one bedroom window, a striking bay or a whole-home renovation. The key is not simply taking a width and drop. It is understanding the space around the window, what may obstruct the panels and how you would like the finished shutters to sit.

For complete confidence, a professional survey is always the best route. Made-to-measure shutters are designed around your individual windows, and an experienced fitter can account for details that are easy to miss. However, taking careful preliminary measurements is very helpful when requesting a quote and deciding which shutter style will suit your home.

Start by deciding where the shutters will sit

Interior shutters are usually fitted either inside the window recess or on the wall surrounding it. This decision affects every measurement that follows.

A recess fit places the shutters within the opening, creating a neat, tailored appearance that works particularly well in bedrooms, kitchens and contemporary rooms. There needs to be sufficient depth for the shutter frame, panels and louvres to operate without catching on handles or other fittings.

An outside-recess fit places the shutter frame on the face of the wall or architrave, surrounding the window opening. It can be an excellent solution where the recess is shallow, uneven or occupied by a projecting handle. It also gives more flexibility to cover an awkwardly shaped opening and can make a smaller window appear more substantial.

Before reaching for the tape measure, stand back and look at the window as a whole. Check for radiators, dado rails, alarm sensors, vents, curtain poles and coving. These do not necessarily prevent shutters from being fitted, but they may influence the frame choice, panel layout or where the shutters need to sit.

How to measure for interior window shutters in a recess

Use a reliable steel tape measure rather than a fabric tape. Measure in millimetres, write every figure down as you go and avoid rounding up or down. A mobile phone photograph of each window can also be useful when you come to discuss your requirements.

Take the width of the recess in three places: near the top, through the middle and near the bottom. Measure from the inside edge of one side of the recess to the inside edge of the other. Older properties across the North East often have openings that are not perfectly square, so the three figures may differ slightly. Record all of them rather than selecting one yourself.

Next, measure the height in three places: at the left, centre and right of the opening. Take each measurement from the top inside edge of the recess down to the sill, or to the point where the shutters will finish if there is no conventional sill. Again, note each figure.

Depth is just as significant. Measure from the front edge of the recess back to the window or the nearest obstruction. Include any handles that project into the space. A window may appear to have a generous recess, yet a handle, tilt-and-turn mechanism or thick glazing bead can reduce the usable depth considerably. This is one of the main reasons a final survey should be left to a professional.

Do not make deductions for clearance unless your installer has specifically asked you to. Shutter frames and panels are manufactured to exact requirements, and the correct allowance depends on the product and fitting method.

Check the sill and surrounding walls

Look closely at the sill. Is it level, deep enough and free from large decorative mouldings? A sloping or uneven sill is not unusual, particularly in period homes, but it needs to be identified early. The fitting solution may involve a carefully shaped frame or a different mounting position.

Also check whether the recess sides are straight. A tape measure gives dimensions, but a visual check reveals bowed plaster, tiled returns or a wall that narrows towards the back. These details are manageable with expert fitting, provided they are allowed for in the design.

Measuring outside the recess

For shutters fitted outside the recess, measure the width and height of the area you would like the frame to cover. In most cases, this means measuring beyond the opening on all sides so the shutters overlap it neatly when closed.

The amount of overlap depends on the available wall space and the features around the window. For example, a narrow strip of wall beside a window may limit how far the frame can extend, while a wide, clear wall gives greater freedom. Measure from the proposed outer edge of the shutter frame on one side to the proposed outer edge on the other, then do the same from the top to the intended bottom position.

Take care with radiators below the window. Full-height shutters can still be possible, but the clearance for opening panels and the route of heat into the room should be considered. In some homes, café-style shutters covering the lower portion of the window offer privacy without interfering with a radiator or reducing daylight above.

Bay windows need a different approach

Bay windows are among the most rewarding places to install shutters. Their clean lines can bring order to a busy shape, improve privacy from the street and make the architecture feel like a feature rather than a challenge. They also demand more than a single overall width.

Measure each section of the bay separately: the left return, centre window and right return. For every section, take the width and drop in three places as you would for a standard recess. Record where the windows meet and take photographs from directly in front as well as from each side.

The angles between the sections are critical. Do not try to estimate them by eye or assume that every bay is a standard angle. Even homes built to similar plans can vary after plastering, decorating or previous window replacements. A professional surveyor uses the correct tools to establish those angles precisely, ensuring the frames meet cleanly and the panels open as intended.

If your bay has a projecting sill, measure how far it extends and note any steps, tiles or decorative details. These features often become part of the finished design, but they must be planned around rather than discovered on fitting day.

Note anything that could affect the shutter design

The measurements tell part of the story; the window’s practical features tell the rest. When preparing for a quote, make a note of the following details:

• the position and projection of window handles, especially on tilt-and-turn windows;

• trickle vents, alarm contacts, sensors and cable routes;

• inward-opening windows or doors close to the shutters;

• radiators, shelving or furniture that may affect panel opening; and

• unusually shaped tops, including arches, angles or very tall windows.

These are not reasons to rule shutters out. They simply help determine the most appropriate configuration. A larger louvre may suit a room where you want a clearer view and stronger sense of space, while smaller louvres can complement more traditional proportions. The way panels divide across the window also matters: it affects how easily you can open the shutters for cleaning, ventilation and access to the glass.

Common measuring mistakes to avoid

The most frequent mistake is measuring only once. Windows are rarely as uniform as they look, especially in older houses, so three width and three height measurements provide a much more accurate picture.

Another is measuring the glass rather than the opening. Shutters are fitted to a frame within or around the recess, not directly onto the pane. Similarly, do not overlook handles and vents simply because they sit behind curtains at present. Shutters occupy the space differently, and every projecting feature needs consideration.

It is also worth resisting the temptation to order from preliminary dimensions alone. Online measurements may seem straightforward, but they place responsibility for tolerances, angles, frame selection and fitting clearances with the homeowner. For a permanent, design-led window treatment, that can be a false economy.

Why a professional survey makes the difference

A survey turns rough dimensions into a shutter specification that works in daily life. The surveyor checks the recess, confirms the final mounting position, assesses practical obstructions and advises on panel configuration, louvre size and material. In moisture-prone rooms such as bathrooms and kitchens, durable PVC shutters may be the sensible choice, while other spaces may call for a different finish to complement the décor.

At The North East Shutter Company, this precision is part of the service rather than an extra for customers to navigate alone. Expert British craftsmanship and careful fitting matter because shutters should close smoothly, sit squarely and continue looking smart for years.

Bring your preliminary measurements, photographs and ideas to the conversation, but let the final millimetres be checked properly. That small step helps ensure your shutters do more than fit the window - they make the room feel finished.