Calculators
Quilt backing and binding calculator.
Enter your quilt top size and fabric width to get the number of backing panels, total yardage for vertical or horizontal seams, a 108 in wide-back option, and the binding strips you need. Everything is worked out in your browser.
Inputs (inches)
Result
Yardage is rounded up to the next 1/8 yd. Inputs stay in your browser and are not stored or sent anywhere.
How the quilt backing is worked out
Backing size. Backing width = quilt top width + overhang; backing length = quilt top length + overhang. The overhang is the total across both sides (default 4 in, so 2 in per side).
Usable width. Usable width = fabric width − selvage trim (default 2 in in total).
Panels. Each seam uses one seam allowance from each of the two panels it joins, so n panels cover n × usable width − (n − 1) × 2 × seam allowance. The tool picks the smallest n that covers the span. With vertical seams the span is the backing width and every panel is cut as long as the backing. With horizontal seams the panels are turned 90 degrees: the span is the backing length and every panel is cut as long as the backing width.
Yardage. Yardage = number of panels × cut length ÷ 36, then rounded up to the next 1/8 yd. The wide-back option is one seamless piece of 108 in fabric (less the same selvage trim), cut whichever way round needs less fabric.
Binding. Binding length = 2 × (width + length) of the quilt top + joining allowance (default 10 in). Strips = that length ÷ usable width, rounded up. Yardage = strips × strip width ÷ 36, rounded up to 1/8 yd.
Sources: arithmetic only, with no external dataset. The 4 in overhang, 2.5 in binding strip, 10 in joining allowance, 1/2 in seam allowance and the 42, 44, 60 and 108 in widths are common quilting and retail conventions, not standards, so adjust them to your pattern and your fabric. Always check the width on the bolt and the instructions from whoever quilts your top.
Quilt backing FAQ
How much bigger than the quilt top should the backing be?
Most quilters add about 4 inches in total (2 inches per side) so the quilt has room to shift while it is quilted and then be trimmed square. Longarm quilters often ask for more, commonly 8 inches in total, so check with whoever is quilting it. This is a convention, not a standard. Change the overhang box to match.
How wide is quilting fabric really?
Fabric is usually sold as 42 or 44 inches wide, but the selvage edges are trimmed off and the fabric can shrink in the wash, so the usable width is smaller. The tool subtracts a selvage trim (2 inches in total by default) from the width you choose. Wide backing fabric is commonly sold at 108 inches. These widths are retail convention, not a standard, so check the width printed on the bolt.
Should the backing seam run vertically or horizontally?
Both work, and the tool shows both. A vertical seam runs from top to bottom with panels side by side. A horizontal seam runs across the quilt with panels stacked, and each panel is cut as long as the backing width. Whichever uses fewer total inches of fabric is flagged as the cheaper layout, but a seam straight through the middle of a quilt can be harder to quilt over, so many people prefer to offset it or use a three-panel layout with a narrower centre strip.
Is a wide-back fabric worth it?
A 108 inch wide-back removes the seam and often needs less yardage than two or three panels of standard fabric, but it usually costs more per yard and is offered in fewer prints. The tool shows the wide-back yardage whenever your backing fits inside 108 inches less the selvage trim in at least one direction.
How is binding yardage worked out?
Add up the quilt top perimeter (twice the width plus twice the length), then add a joining allowance (10 inches by default) for the diagonal joins and the corners and overlap where the binding ends meet. Divide that total by the usable fabric width to get the number of strips, round up, and multiply by the strip width. A 2.5 inch strip is a common double-fold choice. Note that quilters often cut strips wider for thick batting.
Why is the answer rounded up to eighths of a yard?
Cutting tables at fabric shops commonly cut in increments of 1/8 yard, so the rounded figure is what you would ask for. The exact figure is shown too. It is sensible to buy a little extra for shrinkage or a misjudged cut, and this tool does not add any extra for you.