1.800.426.3929
Consider your trim requirements for your door and trim style. These measurement will be your rough opening (WxH) plus some extra to span the door's frame and trim style
You may not need dedicated trim material for your existing window. Sometimes there's extra cedar flooring material (if you selected duckboard). Of course, there will be some extra material that would have covered your existing window's area. It's difficult to estimate that figure here until more details become available