Quilt Backing Calculator
Enter your quilt top size. You get the yardage for both seam layouts, and the cheaper one is highlighted.
How the quilt backing calculator works
The backing has to be bigger than the quilt top so the longarm or your hands have room to work. Most quilters add 4" on every side, so a 60" × 72" top needs a 68" × 80" backing.
Regular quilting cotton is about 42" wide, but only about 40" is usable once you trim the selvages. When the backing is wider than that, you sew panels together. Each seam uses about 1" of fabric. The calculator works out how many panels you need if the seams run up and down (vertical) or side to side (horizontal), then shows the yardage for each. Change the fabric width to 108 for wide backing.
Questions
How much backing do I need for a queen quilt?
A 90" × 108" queen top needs a 98" × 116" backing with 4" extra on each side. In 42" fabric that is 3 panels either way: about 8 1/4 yards with horizontal seams or 9 3/4 yards with vertical seams. In 108" wide backing it is about 3 1/4 yards with no seams.
Should backing seams be vertical or horizontal?
Either works. Pick whichever uses less fabric, which the calculator shows. Some longarm quilters prefer horizontal seams because they roll more evenly on the frame, so ask yours if you are sending it out.
Is 108" wide backing worth it?
For quilts wider than about 72", usually yes. You skip the seams, and the yardage is much smaller. Enter 108 as the fabric width to compare.