Correct measurement for replacement window
I am replacing a large front window opening with vinyl windows from Lowe's. It will actually be 3 double hung windows that will come as one unit from Pella. The actual measurement right now is 66 1/4' tall X 94 1/2" wide. What size window unit should I order? I assume I will need some space on all sides for insulation and squaring it up if necessary. Any advice is appreciated. BTW, I have installed 12 other new vinyl windows in my home so far, so I'm somewhat familiar with the process. Just didn't want you to think I was taking this big one on as my first project..
Thanks,