You input the size of the quilt, add borders (adjust those as you like), and the software does all of that figuring for you. I use a similar program when designing stained glass for my business. Have for years, and love seeing pretty much just how the project will look when complete. I've found it to be well worth the investment in just this first project, alone. It's so fun and easy to create, set and tweak each block. Once the block is set into the quilt design, you can change any or all of the piecing colors. I find this invaluable in balancing the design.