It all depends on what you want to make it. For example my blocks that I made on my first log cabin finished at 12", I started with a 3 1/2 inch center square then made my logs 1 1/2 inch. My most current log cabin quilt the center was still 3 1/2 inch but my logs were 2 1/2 " so my goal here was to make an 18 inch block for a king size quilt. So again it depends on you and how many blocks you want to make. Good luck.