Inside Recess Sizing: Measure the width in two places down the length of the window to check for narrowing. Use the smaller of the two measurements. Measure the drop (height) of the window from the top of the recess to the sill in two places. Use the longer of the two measurements.

Outside Recess Sizing: Measure the width of the blind across the wooden strapping above the window (A–B). If no strapping or facing is present, measure 5cm beyond each side of the window space. If there are window facings, measure the full width of the facing. Measure the drop (height) from the top of the strapping or facing (C–D). If there’s no strapping or facing, measure from 10cm above the window down to the desired blind length.