Measuring for inside mount window treatments is easy peasy!
Step 1: Place end of tape measure inside of the window casing flat against the windowsill.
Step 2: In as straight of a vertical line as possible, extend the tape measure up to the top of the inside of the window casing. Keep the end of the tape measure in the same position as illustrated in step #1 and go straight up!
Step 3: Fold the tape measure in half, so you can grasp the 2 two ends with the same hand, maintaining the center of the fold at the measurement that you took at the top of the window.
Step 4: Now you can pull the measurement down to eye level to view. Round up – I would say this window is 71” high!
Step 5: To measure the width, lay the tape measure as flat as possible in a straight line, do not create a diagonal across the windowsill with the tape measure. This window is 32.25” wide!