Always use a metal tape for accuracy. Please use metric measurements. Firstly, work out whether you would like your blind to fit outside the window recess or within the recess / window frame.
Inside Recess
Measure A in several places in case the walls are not straight. Write down the smallest measurement
Measure B as above
Double check
Outside Recess
Measure the area you wish to cover. We recommend you make the blind 20cm wider than the window (10cm either side) and 7.5cm higher - but you may want to change this.
Measure A and B carefully and double check.
We will always make a slight deduction from inside recess measurements, to ensure the blind fits nicely within the recess. For more information see blind mechanisms.