Follow these simple 5 steps to measure your roman blind
Metal tape measure
Measure width from the outer edge of the frame on the left to the outer edge of the frame on the right, then add 100mm (i.e; 50mm to either side).
For the height (drop) measure from the top of the frame to the lowest point of the frame, then add 150mm (i.e; 100mm above the top of the frame and 50mm below the frame).
Choose your chain control side. Usually the most convenient side to get to
control chain colour