Size Squares?
 

What size squares do I cut out to make an 12 1/2" unfinished disappearing 9 patch quilt block?
I have never made one before so I wanted to make sure. Thank you for any help on this.

Unless you want to cut some unusual fractions, you can't get it to come out to 12-1/2". If you start with 5" squares for your 9-patch, it will make a finished block of 13". Starting with 4-1/2" squares will get you 11-1/2" finished. Starting with 4" squares will finish at 10". You could go smaller and add borders to the blocks, or use any of the sizes above and adjust your quilt border sizes to make the quilt a certain size.

here's a page that talks about the sizes of the starting/parent squares
http://quilting.about.com/od/blockof...-Pattern_3.htm

Hi June Billie. I am not sure but I wonder if the "D9P block" measurement includes 4 units sewn together. I am NOT hip on all the latest so I do mine and lay each individual unit as a block. I am fussy with laying out my scrappy quilts. I cut 6.5" square and my single block is 9" unfinished. I wish you the best of luck. This math is just driving me up a wall. Hang in there !! Here are some of the blocks I am working on. Thinking of setting them on point. I don't know if anybody has done that before.

That quilt top is very pretty. The math is crazy. lol.. I may go for another block, and use this one for a better size block. Thanks everyone for your help. I know this is the best place to find it.