Window measuring
Measuring Guide
Accurate measurements are the foundation of a perfect fit. Follow the steps below to measure your windows with confidence, whether you are ordering for an inside recess or an outside mount.
Before you begin
Measuring basics
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Use a steel tape
Always measure with a steel tape, ideally 2 cm to 2.5 cm (¾″ to 1″) wide, for consistent and accurate readings.
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Width, then height
Measure width first, then height. Width is listed first when you order, so this sequence helps prevent transposing the two dimensions.
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Record immediately
Write down each measurement as soon as you take it. Do not rely on memory, however confident you feel in the moment.
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Measure every window
Measure each opening individually, even when windows appear to be the same size. Small differences are more common than you might expect.
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Check for obstructions
Inspect the opening for anything that may interfere with fitting or operation, such as protruding latches, handles, or uneven reveals.
Measuring for an inside recess
For blinds fitted within the window opening, take three measurements for each dimension and use the smallest figure.
- Measure the opening width at the top, centre, and bottom.
- Measure the opening height at the left, centre, and right.
- Record the smallest width and smallest height from your readings.
- Measure both diagonals. If they are not equal, the opening may be out of square — consider an outside mount for better privacy and light control.
Inside mounting depth
If the blind cannot sit fully within the recess, part of the fitting will project beyond the opening. Add any extra clearance required for latches, handles, or other obstructions to your minimum mounting depth measurement.
Measuring for an outside mount
For blinds fitted to the wall or frame surrounding the opening, measure the finished size you require rather than the recess alone.
- Measure the desired width and height at the centre of the window opening.
- Allow for the recommended overlap for your chosen product to minimise light gaps at the edges.
- If the window has moulding and you are not mounting onto it, ensure your height measurement allows the blind to be fitted above the moulding.
When to choose outside mount
Outside mounts are often the better choice for uneven openings, shallow recesses, or when maximum light exclusion is important.
Need a second opinion?
If you have read our guides and would like further advice, send us a photograph of your window by email or call our team — we are happy to help.