I always use a double 1" hem on each side and a double 2.5 on the hem. The extra weight on the double hems help them hang better. You will need about 2.5 times the width, this does not have to be exact! I usually round it up depending on width of window. So a 30" curtain rod, divided by 2 (left and right panels) = 2-15" panels. If the fabric is 44" wide? 15x2.5=37.5"panels- so I would cut 2 panels 44" wide. Made a 1" hem on each side. Then calculate your pinch pleat width and space width after.
The pleat will be aprox 5 in. You will need extra inches for spring back. Springback is the extra sag that developers in pinch pleat drapes when hanging. So after sewn you really want more than 15" on each panel. You also need overlap, for the middle, where the panels meet, so there isn't a gap in the middle. If you want to continue with these I can help you with # of pleats and pleat size and space size.