Preparing the quilt back is an important step to finishing your quilt. If knowing how much fabric you’ll need or how to piece it is challenging, this will help you.
How to determine the yardage needed for the back of your quilt:
NOTE: These instructions assume that you have 42” of usable fabric from selvage to selvage, once the selvage is removed.
Measure the width and length of the quilt and add 8” more to each measurement. Many long-arm quilters want you to add at least 4” to each side for quilting. If you are machine quilting a smaller piece on your sewing machine, you can get away with not having as much extend beyond the top. A table runner might only need several inches on each side, for instance.
If the width of the quilt is less than 40” across, you won’t have to piece your back. You will need to purchase enough fabric to accommodate the length off the quilt top. Take the length measurement, divide that number by 36” (the number of inches in a yard), and round up to the next 1/8” increment. That’s how much fabric you’ll need. (A quilt that is 40” would need 1 ¼ yards of backing.)
If the width of the measurement is less than 84” across, you will have to use two pieces to piece your back. Take the length measurement, multiply that number by two, divide that number by 36” (the number of inches in a yard), and round up to the next 1/8” increment. That’s how much fabric you’ll need. This piece of fabric would be cut into two sections.
If the width of the measurement is more than 84” across, you will have to use three pieces to piece the back. Take the length measurement, multiply that by three, divide that number by 36” (the number of inches in a yard), and round up to the next 1/8” increment. That’s how much fabric you’ll need. This piece of fabric will be cut into three sections.
You will need to use decimals to figure out the next increment. For instance, “.25” would mean ¼ yard. A measurement of “.33” would mean 1/3 yard. “.50” would mean ½ yard.
How to sew a pieced back:
For two pieces, you can seam them so that the seam will be down the center of your quilt, or you can ask your quilter to adjust the quilt top so that you have a larger piece of usable fabric when the excess is removed.
When sewing three pieces, many people like the look of a wider center fabric, flanked by two narrower pieces. To do that, you’ll need to slice one of your cuts of fabric in half along the fold.
Some people believe that sewing the pieces along the grainline keeps the backing stronger.
Sometimes you may need to make allowances for piecing your back based on preference or the amount of fabric you have. It’s ok to mix fabrics for a scrappy back. Do what works best for you and the fabric you intend to use.
Trim the selvages from the fabric before you seam the edges.
Sew the seams with a half inch seam allowance.
Press seams open, and press the fabric before beginning to quilt.
Make the back of your quilt as pretty as the front so that when the quilt top flips over, the user still gets a colorful experience.