Quilt Backing Calculator
Backing yardage, with overhang and panel seams.
Calculate quilt backing yardage including the overhang a longarm needs and the panels required when the quilt is wider than the fabric.
4" is what most longarm quilters ask for. 2-3" is enough on a domestic machine.
Backing needed
5.00 yd
2 panels · 68" × 88"
Two panels means buying the full backing length twice over, not the difference — which is the step that surprises people. Extra-wide backing at 108 inches removes the seam and is usually cheaper above about 60 inches of quilt width.
How the Quilt Backing Calculator works
Backing is where quilt yardage goes wrong, because two things multiply at once. The backing has to be bigger than the quilt on every side, and once it is wider than the bolt it needs a second panel — which means buying the full length twice over, not the difference.
Also known as: backing yardage calculator · quilt back fabric calculator
Why the second panel costs so much
Backing has to exceed the quilt on all four sides — four inches a side is what most longarm quilters require, because the frame clamps the edges and needs something to hold. A 60 by 80 quilt therefore needs a 68 by 88 piece of backing.
Fabric comes off a bolt at a fixed width, usually 42 to 44 inches with about 41 usable. Once the backing width exceeds that, a second panel is needed, and the panel runs the full length of the backing. That is the step that surprises people: going from a 40 inch backing to a 42 inch one does not cost two inches of fabric, it costs another 88 inches.
Panels are conventionally cut along the length and seamed down the middle, which puts one vertical seam in the back. On a wide, short quilt, running them across instead can use less fabric.
A worked example
A 60 by 80 quilt with four inch overhang needs 68 by 88 of backing. At 41 usable inches per panel, 68 inches of width needs two panels. Each is 88 inches long, so the total is 176 inches — 4.9 yards, bought as five.
The same quilt on 108 inch extra-wide backing needs a single 88 inch panel: 2.4 yards. Even at a higher price per yard, wide backing is usually cheaper above about 60 inches of quilt width, and it removes the seam entirely.
Where the answer misleads
The seam allowance between panels eats into the usable width, which is why the calculation uses 41 inches rather than 42. On a backing that lands within an inch of a panel boundary, that allowance decides whether you need one panel or two.
Directional prints on the backing are a trap. A print that must run the same way on both panels can waste a great deal of fabric, and a print with an obvious repeat will show any mismatch at the seam. Plain or tossed prints are far more economical for backing.
Finally, four inches a side is a longarm requirement. Quilting on a domestic machine needs only two or three, and quilting it yourself on a frame you own means you can decide. Ask the quilter before buying.
Frequently asked questions
How much bigger should the backing be?
Four inches beyond the quilt on every side is what most longarm quilters ask for, so a 60 by 80 quilt needs a 68 by 88 backing. Quilting on a domestic machine needs less, two to three inches a side.
When do I need two panels?
When the backing width exceeds the usable fabric width, about 41 inches on a 42 inch bolt. A 68 inch wide backing needs two panels seamed together, each cut to the full 88 inch length — so 176 inches in total, not 88.
Should the seam run across or down?
Down the length is conventional and uses less fabric on a long quilt; across is better on a wide short one. Whichever direction uses fewer whole panels is the cheaper one, and the calculator assumes lengthwise panels.
Can I use extra-wide backing fabric?
Yes, and for anything over about 60 inches wide it is usually cheaper. Wide backing comes in 108 inch widths, which covers most quilts in a single panel and removes the seam entirely.