I played with this, started with the larger sizes, but didn't like how much fabric was all around the center. So I went smaller. Still didn't like the center so small and too much fabric aroud it. So using about a 4" square, I used 4 - 4" square and then the middle one I went with 5". Liked it better. I think that what ever size block you use, if you want a larger center, just don't go over 1/2 (minus your seam allowance) the measuement of the other 4 blocks. It can be made any size.