Horizontal Blind Measurement Guide
For an inside or recessed mount:
Measure the exact width of the window opening from the inside of the trim to the inside of the trim on the other side. As some windows are not a perfect square, take this measurement in three places (top, middle and bottom). Round the measurements down to the nearest 1/8" and record the narrowest (smallest) measurement.
Measure the exact height of the window opening from the inside of the trim to the top of the windowsill or to the exact length that you want the blind. Measure the height in three places (the right side, the middle, and the left side of the window). Round the measurements down to the nearest 1/8" and record the shortest (smallest) measurement.
Measure the available depth of your window frame. Be careful not to include inside trim, window cranks or tracks. Measure only the space that is available to install the mounting brackets for the blinds. Record the measurement.
For an outside mount:
Outside mounts hang outside the window opening either on the wood trim or above and on either side of the wood trim.
If you want to mount your window blinds directly to the window frame, then measure the exact width of the wood frame itself from outer edge to outer edge. Round this measurement down to the nearest 1/8" and record it.
Measure the exact height from the outer edge of the top of the trim to the top of the windowsill or to the exact length that you want the blind. Measure the height in three places (the right side, the middle and left side of the window). Round the measurements down to the nearest 1/8" and record the shortest (smallest) measurement.
If you have enough room on each side of your window and would like to ensure maximum privacy and minimum light gap, measure the exact width beyond the wood trim that you would like to have the blind cover. With horizontal blinds, it is generally recommended to add at least 1" to 3" beyond each side of the window and at least 2 ½" to 3" to the height to allow space for mounting brackets above the opening of the window and to add your desired overlap at the bottom of the window opening.
| 
