124.6 cm = 1246mm
135 cm = 1350 mm
Inches x 25.4 = mm
Take these measurements to a shutter company in the neighborhood and they would let you know about the options available for you.
These numbers should be sufficient for a shutter company to show you different options of window treatments for you.
Before getting the plantation shutters designed, talk about your specifications! They need not be the standard design that every house in the neighborhood has.
You could choose a double-hung shutter if you’d like to leave one of them open while the other one is closed. You could also take your pick from a bi-fold shutter that opens to one side or one that opens from the center to both sides.
These measurement techniques can also help you to build exterior shutters yourself. You will need more detailed measurement techniques then.