It looks as though the large center rectangle is about 2x as tall as the rows above/below. I would decide what you want for a finished size, divide that in 2 to get the height of the center, then divide the rest of it in half. Same thing for the width.
For instance, if you want it about 60x80, you could make the center 30x40, 2 pcs 20x30 (top/bottom), 2 pcs 15x40 (sides) and the corners 15x20. I did not add seam allowances, but if you are flexible with the size, you could just cut as is. With this type of pattern, you can be very flexible with your sizes.
Last edited by katier825; 06-27-2014 at 06:16 AM.
Reason: added diagram