Practical tools for measured work
Quilt Backing Calculator & Panel Layout
Compare vertical and horizontal backing-panel layouts, yardage or metres, seams and waste from your quilt and usable fabric width.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
Use the unit selected above.
Use the unit selected above.
4 in is a common longarm-friendly starting allowance.
Measure after excluding selvages; try 108 or 118 in for wideback.
Cut 2 pieces, each 88 in long. The recommendation minimizes rounded purchasing length, then waste; it does not compare price.
How it works
Direct answer: enter the finished quilt-top size, extra backing on every edge and usable fabric width. The calculator tests seams running vertically and horizontally, then shows both purchasing quantities.
Method: required backing equals the quilt dimension plus twice the edge allowance. One panel covers the usable fabric width; each additional joined panel contributes that width minus two seam allowances. Purchasing rounds up to the next quarter yard or 0.1 metre.
Example: a 60 × 80 in top with 4 in extra per edge needs a 68 × 88 in backing before trimming.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Measurement unit
- Inches
- Quilt-top width
- 60
- Quilt-top length
- 80
- Extra on each edge
- 4
- Usable fabric width
- 42
- Backing seam allowance
- 0.5
Primary result: Backing size: 68 in × 88 in.
Before using the result
- Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
- Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
- When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.
Limitations
Fabric can shrink, skew and vary in usable width. Confirm longarm or quilter requirements before buying. The diagram shows panel arrangement, not print scale, and does not compare fabric prices or place a directional print.
Frequently asked questions
Should backing be larger than the quilt top?
Yes. The entered edge allowance is added on all four sides. Four inches per edge is a common starting point, but your quilting method or longarm provider may require another amount.
What is usable fabric width?
It is the width available after removing selvages. A bolt labelled 44 inches may provide about 40 to 42 usable inches, so measure or use the supplier specification.
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