How to measure your windows for shutters: a complete guide

This guide covers exactly how to measure your windows for shutters, from choosing the right fitting method to recording precise dimensions. It gives you a clear measuring guide for measure windows for shutters, so you can order with confidence and avoid costly mistakes.

How to measure your windows for shutters accurately

Plantation shutters are custom-made to your window measurements, so even a small error can affect the fit after installation. Use a steel tape measure, work in millimetres, and write down every figure as you go.

Inside recess vs outside fit: choosing your installation type

That starts with the fitting method. If you’re wondering how to measure your windows for shutters, start by choosing between an inside mount and an outside fit, because your window type, window depth and the condition of the window frame all affect the method. An inside mount sits inside the window opening, while an outside fit fixes beyond it onto the wall or trim.

• Inside recess: this needs a minimum window depth of 45mm for 76mm blades or 50mm for 89mm blades.
• Outside face fit: this suits shallow or uneven frames and gives wider coverage across windows for shutters.
• Square check: measure the diagonal corner to corner in both directions; if the two figures differ by more than 5mm, the opening is not square.
• Obstructions: note window handles, locks, tiles, sensors and other obstructions, because an inside mount usually needs 50–75mm clearance from the front edge of the recess.

That square check often decides the safer route. Outside mounts are used in around 85% of installations because many windows for plantation shutters are not perfectly square. By contrast, an inside mount is the right choice when the recess is deep enough, the window opening is true, and nothing projects too far into the space.

Step-by-step measuring guide for standard windows

Once you’ve chosen the fitting style, measuring windows for shutters follows a clear sequence. Measure the width and height in three places each: for window width, take the top, middle and bottom; for window height, take the left, centre and right. Record the smallest figure on each axis: that is the dimension you submit for an inside recess.

From there, one point matters. Do not make your own deductions. Shutters365 applies any manufacturing allowances during production, so your job is to measure the width and height accurately and provide the exact window size you see inside the window. The custom shutters guide shows how window width, window depth, the window sill and the shutter frame all influence the final specification.

Measuring bay windows and other special window types

Once the standard method is clear, the same logic applies to more complex layouts. Measuring windows for plantation shutters in bay windows works best when you treat each section separately and sketch the whole arrangement first. Measure each panel inside the window frame, taking the width and height corner to corner, then label every section clearly.

That section-by-section method helps with angles. For bay windows, paper templates cut to L-frame specifications can confirm positioning at each return: 47mm × 37mm × 19mm. Measure from the window sill to the top of the recess for the full window height, and keep each section’s figures separate so the shutter frame can be made to suit.

From there, the difference comes down to shape when you move beyond bays. Arched window shapes need the widest point and the full rise from base to apex, while sash windows need enough clearance above the frame so plantation shutters do not interfere with movement. French doors should be measured panel by panel, with extra attention to window handles and other projections inside the window opening.

The shutter measurement tool accepts dimensions for standard windows, arched designs and other awkward window shapes, including windows for plantation shutters with projecting sills.

Avoiding common measurement mistakes before you order

Once those special cases are covered, the usual problems become easier to spot. If you’re learning how to measure windows for interior shutters or measuring windows for shutters for the first time, the common issues are usually missed diagonal checks, overlooked obstructions, or measuring only once. A window frame can look square and still be out enough to affect the fit.

As a result, the practical check is simple. Measure the diagonal both ways, note any clearance issues around window handles, tiles, locks or reveals, and photograph the full opening as well as any detail that could affect the shutter frame. This matters even more where the window sill projects or the recess narrows towards the front.

Once you’ve measured, Shutters365 offers a free verification service. You can submit your window measurements and photos before production, and the team will review them at no cost. That extra check is especially useful for bay windows, arched frames and any other window type where you want reassurance before ordering.

Frequently asked questions

Do plantation shutters fit all window sizes?

Plantation shutters fit most window sizes because they are made to your recorded width and height.

That matters most with an inside mount. The key check is window depth: for 76mm blades, the minimum recess depth is 45mm inside the window. If your windows for plantation shutters have a projecting sill, an All with Sill Cut frame allows the shutter to sit properly once fitted.

Narrow or tall rectangles are straightforward; shaped windows add one further variable. Arched designs and bay windows are possible, although the difference comes down to a more detailed measuring guide and a careful check of the window frame.

How do I measure the window width and height if my frame is not square?

A frame that is not square will distort an inside-mount panel: check the diagonal from corner to corner. If the two diagonal measurements differ by more than 5mm, the frame is not square.

Where that happens, you should still take the window width at three points and the window height at three points. Record the smallest measurement on each axis, as this gives the accurate window measurement needed for production.

Where the frame is noticeably out, the right choice when ordering is usually not an inside fit. An outside face fit fixes beyond the window opening, so it is not affected in the same way by an uneven frame. If you measure your windows for plantation shutters and the frame seems significantly out, Shutters365 can check your photos and measurements before production starts.

What should I do if window handles or other obstructions are in the way?

Those measurements also need to account for window handles and other obstructions.

For an inside mount, measure from the window frame to the furthest point of the handle, then compare that with the available clearance at the front of the recess: you need around 50–75mm. This is worth knowing before you order, especially if the handle projects into the shutter’s path.

If there is not enough space, fitting inside the recess is unlikely to work. An outside mount avoids the problem altogether because it sits beyond the recess rather than inside the window. When you measure your windows for plantation shutters, include photos of all obstructions so Shutters365 can verify the details.