The treatment needs four panels.
How many panels curtainsfor door opening.
Add 12 inches to each side 24 inches total.
For example if you have a 28 inch wide panel and a 36 inch curtain rod purchase two panels for minimum fullness three panels for medium fullness and four panels for extra fullness.
If you want your draperies to cover the entire window you will need enough panel width to hang across the full opening.
In regards to the length of the curtains you ll want curtains that extend 3 inches above the door frame and 1 inch below the door frame so that the curtains are grazing the floor and not covering the top of the door frame.
For example if the package lists the curtain as finished at 25 inches wide and the area to cover is 100 inches 100 divided by 25 equals 4.
So a pair of 48 wide drapes can cover 48.
It will not take up much wall space at all.
You need to factor in the overlaps which we usually consider as 12 center area where the left and right panel should overlap each other when closed and returns the wrap around part which returns from the face of the rod to the wall so a 48 pinch pleat pair really covers about 36 of area.
You want a pair of panels for each window one width of fabric for each panel.
Take the total number width plus the number you added to each side and divide that number by how many drapery panels you want in the window.