How to measure your windows

Five minutes with a steel tape is all it takes. Work in feet and inches, write everything down as width × height, and never reuse one window's numbers for another.

1. Step 1

   Decide inside or outside mount

   Inside mount sits within the window recess for a neat, built-in look. Outside mount fixes to the wall above the opening and blocks more light — the right choice for shallow recesses and blackout bedrooms.

2. Step 2

   Measure the width in three places

   Top, middle and bottom. For inside mount, use the narrowest measurement. For outside mount, add 3 inches on each side for overlap.

3. Step 3

   Measure the height in three places

   Left, centre and right. Inside mount uses the longest drop; outside mount adds 4 inches above the opening for the bracket.

4. Step 4

   Note obstructions

   Handles, grills, AC units and deep sills change the mount type. Photograph anything unusual and send it with your enquiry.

5. Step 5

   Double-check before you order

   Self and AR measurements are estimates — measure twice with a steel tape to confirm before placing your order.