double or even triple fullness so 72 x 2= 144 I would use 2 50” panels on each side for a nice full look

It depends on how the curtains are made. If they are to be gathered, you want what Patricia has said--double or triple the width. If they are pinch pleated drapes or drapes that do not get gathered, you just need to purchase drapes that are wide enough to clear the window on both sides by at least 10" or more.