Gather your tools: Grab a metal measuring tape, a notepad, and a pen or pencil to jot down your measurements.
Decide on the mounting type: Roman blinds can be mounted inside or outside the window frame. Determine which option you prefer and proceed accordingly.
Measure the width: Measure the width of the window at three points: the top, middle, and bottom. Take the smallest measurement of the three as your window width. Record the measurement.
Measure the height: Measure the height of the window at three points: the left side, middle, and right side. Take the largest measurement of the three as your window height. Record the measurement.
Deduct allowances: For the inside mount, you'll need to deduct a small amount to ensure a proper fit and smooth operation of the blinds. Typically, deduct around 1cm from the width to allow for clearance and smooth operation.
If you have a part-tiled recess (in kitchens and bathrooms) then the space between them is most likely to be the narrowest point in the recess.
Measure the width: Measure the desired width of the blind. For outside mount, it's common to extend the width beyond the window frame to create a larger appearance and provide better light control. Decide how much overlap you want on each side and add it to the window width measurement. Record the final width measurement.
Measure the height: Measure the desired height of the blind. Decide how much coverage you want above and below the window frame and add those measurements to the window height. Record the final height measurement.
Consider brackets and clearance: Keep in mind that you'll need to account for the size of the mounting brackets when measuring for outside mount blinds. Ensure that your measurements provide enough space for the brackets without obstructing any window or door handles.