Quilt Backing and Batting Calculator

Enter the finished size of your quilt top. The calculator adds the overhang your quilter needs, works out how many widths of fabric that takes, and tells you the yardage with the seam layout. Backing is the purchase people most often get wrong, usually by forgetting the overhang.

Why the overhang is not optional

A longarm quilter loads the backing onto rollers and needs fabric to clamp beyond the quilt top on every side. Four inches all round is the usual request, which means eight inches added to both the width and the length. Turn up with a backing cut to the exact size of the top and it cannot be loaded at all. If you are quilting on a domestic machine, two inches is enough, but it still is not zero.

Seams, selvedges and direction

Trim the selvedges off before joining panels. Selvedge is woven more tightly than the rest of the fabric and will pull the seam in as soon as it is under tension. Press the joining seams open rather than to one side, so there is no ridge for the quilting needle to climb over. The calculator picks whichever seam direction uses less fabric, which is not always the direction you would have guessed.

Batting

Buy batting to the same measurement as the backing. Precut packages are sold in bed sizes that are generously cut for exactly this reason. Cotton batting usually wants quilting every 3 to 4 inches, polyester up to 8, and wool somewhere between; check the package, because that number decides your quilting density more than the design does.