How to measure
HOW TO MEASURE
Be sure to measure accurately. If the window is set in a deep recess, fitting the blind inside makes for a neat finish. But mistakes in measurements can ruin them altogether.
Measure the width. Measure the width of the recess in three places: at the top, at the middle, and at the bottom. Make sure you hold both ends of the tape on the inside edges of the recess. Note the smallest measurement, as it will be the one you use.
Measure the height. Measure the height of the window recess three times: at the left, in the center, and at the right. Make sure you hold both ends of the tape on the inside edges of the recess. Note the smallest measurement, as it will be the one you use.
Measuring for Outside-Mount Blinds
Determine where the mount will be. It should be placed 1 1⁄2 to 3 inches (3.8 to 7.6 cm) above the window.
Measure the height. Measure from the proposed location of the mount down to 2–4 inches (5.1–10.2 cm) below the bottom of the window. This extra overlap is to block out light and ensure privacy.
Measure the width. For the width of any set of blinds, carefully measure the width of the window and add between 2 and 4 inches on each side.
Inside & outside diagram