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How to measure for replacement windows

Windows that fit perfectly

You’ve made the decision to replacement your home’s windows and now you’re asking “how do I measure for replacement windows?”

As you’re aware, it’s important you take the right measurements. So here’s our guide to measuring for a replacement window.

When measuring for replacement windows on Windowlines, always think width x height, and take your measurements from the outside of your house.

The width:

  1. Take 3 horizontal measurements in mm at the top, middle and bottom in mm.
  2. You need to place your tape measure at the widest part.
  3. Note the smallest measurement and take off 10mm. This is your replacement window’s width.

The height:

  1. Take 3 vertical measurements in mm on the left, centre and right in mm.
  2. Between top (head jam) and bottom (cill) at the widest part
  3. Note the smallest measurement. This is your replacement window’s height

The cill:

  1. Measure the depth of your jam at the deepest part of your window.


Download these instructions

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