Quilt backing calculator
Work out how much backing fabric your quilt needs, how many pieces to join, and which way to run the seams so you buy the least fabric.
How quilt backing is worked out
- Add the extra on every side to the quilt top: a 60 × 70 inch top with 4 inches extra needs a 68 × 78 inch back.
- Divide the backing width by the usable fabric width (about 40 inches for quilting cotton) and round up: that is how many pieces to join.
- Each piece is as long as the other side of the backing. Try both directions and use the one with less fabric.
Also need binding and batting? The quilt calculator works out all three, and the quilt binding calculator gives the strips to cut. Standard sizes are in the quilt size chart.
Questions
How much fabric do I need for a quilt back?
Add the extra your quilter asks for (usually 4 inches on every side) to the quilt size, then work out how many widths of fabric that takes. A 60 × 70 inch throw needs a 68 × 78 inch backing: two 68 inch pieces of standard quilting cotton sewn together, which is 3 7/8 yards.
Should the backing seam run up and down or across?
Whichever uses less fabric. The calculator tries both and tells you which way to sew the seams. For many throws and queen quilts a seam across the quilt saves a yard or more.
How much bigger than the quilt top should the backing be?
At least 4 inches bigger on every side (8 inches in total each way) for longarm quilting, and 2 to 3 inches for quilting at home on a domestic machine. Check with your longarm quilter.
What is wide back fabric?
Backing fabric that is 108 inches wide, so most quilts need just one piece with no seams. Choose it under Backing fabric to compare.
Why is the answer rounded up?
Fabric is cut in eighths of a yard, so the calculator rounds up to the next 1/8 yard. Buy a little extra if you will pre-wash, as cotton can shrink.