How to calculate it
Add twice the side allowance to each quilt dimension. Allow 1 in of width for each join (two ½ in seam allowances), then round up to the number of lengthwise panels. Multiply the panel count by the backing length, then divide by 36 for yards.
Worked example
A 60 × 72 in top with 4 in extra on each side needs a 68 × 80 in backing. Two 80 in panels require 160 in, or 4.44 yd before seam, squaring and print-matching allowances.
Before you cut or buy
- Measure usable width after removing selvages. Joining seams reduce the finished width; add another panel if the estimate is close to a threshold.
- A longarm quilter may require more overage or a different seam orientation. Confirm their requirements before cutting.
Common questions
How much extra backing should I leave for longarm quilting?
Four inches beyond every edge is a common starting point, so add eight inches to the top's width and length. Your longarm quilter may request more for their frame, clamps or dense quilting; follow their requirements before you cut.
Why does the panel count change suddenly?
Whole fabric widths are joined. If the target backing is just wider than the usable joined widths, you need another full length of fabric. Measure after selvage removal and include the width consumed by joining seams.
Planning a queen quilt? Read our queen quilt backing yardage guide for 42-inch and 108-inch examples, cutting instructions and longarm advice.
Use your own measured materials and pattern instructions. Estimates cannot account for every variation in technique, shrinkage or layout.