I agree with Prism99. But if the quilt is over an inch in difference between the measurement of the center to the outside edge, you need to be a detective to find out where your seam allowance went awry or if it was the blocks not all being the correct size. That is why I prefer taking the time to check each block is the correct size. I would rather oversize my blocks and trim them down so that each one is the same size. Then you have no problem with a difference of the the center of your quilt compared to the outside measurement. Just finished sewing the blocks together.