Do you really need the quilt backing and batting to be 8″ larger than the quilt top? I don’t cut them that big if I’m hand quilting or quilting on my domestic sewing machine (DSM)!
There are several reasons why I ask for the batting and backing to be a total of 8″ wider and 8″ longer than your quilt top. When you are hand quilting or quilting on your DSM, you baste the layers together before starting. Since you lay everything out flat, it allows you to see if you are going to come up short in one area or another BEFORE you ever start the quilting process. Then you can make adjustments so you don’t run out of backing over there in the lower left corner, or wherever.