It depends in which way you want to enlarge it. I added two more columns and 4 more rows. If I calculated correctly you would need 1/2 yard more of the strip fabrics/two outsides (2" x 37") , 27" more fabric of this strip fabric/middle (3" x 3") , the Squares A would need 1 1/3 yards more. These are pretty close measurements and I would probably purchase a bit more. I didn't figure out the borders.