Measure the width of each window opening from inside edge to inside edge to the nearest 1/4 inch, excluding any framing or molding. Take three measurements: one at the top, one in the middle, and one at the bottom of the window. Record the smallest measurement.

If the window will have shutters on either side, this number is your “Pair Width”. For stand-alone windows that only require one shutter, this number is your “Shutter Width”.

Important Note: Substract 1/2 inch from your width measurement to allow for proper clearance when opening and closing.