Use a metal tape and measure the recess of the window at three different points, as it may not be the same along the entire recess. Measure at the top, middle and bottom and use the smallest measurements as your width guide.
To measure for the length of the blind, use the metal tape and measure from the top of the recess to the windowsill at 3 different points and note the narrowest point. For vertical blinds, we recommend you reduce the length by 1cm to prevent the fabric from catching on the sill.
Measuring windows without a recess
Use a metal tape and measure across the window width, adding an extra 10cm (4″) to the total width to allow a 5cm (2″) overlap either side of the window to block out light effectively. For roller blinds add a further 5cm (2″) to the width to allow room for the operating mechanism.
Decide where you want the bottom of your blind to end and measure the length of the window from the top of the fitting to this point.