You need decide how large you want to make a single block. So, for instance, if the block you choose finishes at 12 inches square, you would need 5 across and 5 down, or 25 blocks. This will give you a 60X60, then add some borders to make it a bit larger. If your block finishes at 9", then you would need 7 across and 6 down, or 42 blocks. This will give you a 63 by 54 body, add some borders, etc. All depends on the finished size of the block you choose.