I generated a QR code and than made a grid. All squares are the same size so the grid is simple. Count the number of squares in one direction and multiply by inches finished. If there are for example 30 squares x 2" = 60" width. With seam allowance of 1/4" your squares need to be 2.5 x2.5". This is just an example. I do not have my design book in front of me. Good luck! I am in planning stages as well. I have no time right now for such an involved project.