How to Measure Your Windows

Getting your measurements right is critical. All our windows are manufactured to your exact dimensions — we cannot accept returns on incorrectly measured orders. This guide takes 5 minutes to read and will ensure your windows fit perfectly first time.

What You Will Need

A steel tape measure (not a fabric one — these stretch and give inaccurate readings)
A pencil and paper to note down measurements
A step ladder if your windows are high

Important: All measurements on our configurator are entered in millimetres (mm). Convert any inch measurements before entering your size.

Step-by-Step Guide

Measure the Width

Measure the width of the existing window frame from the outermost edge on the left to the outermost edge on the right. Do not measure the glass or the visible frame — measure the full frame including any part hidden in the wall reveal.

Take three measurements: top, middle and bottom. Use the smallest of the three.

Measure the Height

Measure the height of the existing window frame from the very top edge to the very bottom edge, again including any part set into the wall reveal.

Take three measurements: left side, centre and right side. Use the smallest of the three.

Check the Reveal Depth

The reveal is the depth of the wall surrounding your window. Most standard UK properties have a reveal depth of 90–150mm. If your reveal is unusually shallow (<70mm) please call us before ordering as a frame extension may be required.

Note the Sill

All our windows are supplied with a uPVC window sill included. The sill is sized to match the window width and is included in the price shown. If you require a longer sill to cover a wider reveal, please note this when submitting your quote.

Replacement Windows

If you are replacing an existing uPVC window like-for-like, simply measure the overall outer frame size of the existing window. Our replacement windows are manufactured to the same overall dimensions so they drop straight into the existing opening.

New Build or Structural Opening

If you are fitting into a new brick or structural opening rather than replacing an existing frame, measure the structural opening and deduct 10mm from both the width and height to allow for fitting tolerances and expanding foam.

Double-check before ordering. Once your order is placed and manufacturing begins, we cannot amend dimensions. If you are unsure about your measurements, call us on 0800 861 1450 before ordering and we will be happy to advise.

Toughened Glass

Building Regulations require toughened safety glass in certain locations. You must select toughened glass if your window is:

Within 300mm of a door (measured from the edge of the door)
Less than 800mm from floor level
In a bathroom or en-suite
In a stairwell

You can add toughened glass using the toggle in our configurator. There is a 15% surcharge for toughened glass.

Common Mistakes to Avoid

Measuring the glass size rather than the frame size
Using a fabric tape measure
Taking only one measurement instead of three
Entering measurements in centimetres instead of millimetres
Forgetting to allow fitting tolerance for new structural openings

Ready to get your price? Enter your measurements directly into our configurator for an instant quote.

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