Originally Posted by QuiltE
Always start with the size you want it to finish at (after all the seams are in the quilt).
So ... for a 6" finished 4P block ....
* each of the 4Ps would be 3"x3" finished
* add on 1/4" for seams on each side
* each of the 4Ps would be 3-1/2"x3-1/2"
You can do the same for 9Ps .... and most anything else! Keep this, and you're on your way to designing your own patterns, or looking at a photo and figuring it out!
Just remember you need to add 1/2" for seam allowances to your solid squares as well to get to the same size!