Use the same panel geometry as other backing fabrics, but make the fabric-preparation decision before relying on its dimensions. This guide does not assume a standard shrinkage percentage.
Choose the fabric with the whole quilt in mind
Check the flannel’s fiber content, care and weight. Test it with the intended top and batting, and confirm any longarm requirements.
Measure after the preparation you intend to use
Follow the product’s care guidance; measure usable fabric after your chosen preparation.
Follow product instructions. If washing and drying before construction, measure usable width afterward. A representative before/after sample can inform planning; no universal flannel shrinkage rate is assumed.
Keep the preparation calculation separate
If a sample retains fraction R of its length, starting length ≈ required prepared length ÷ R. R = length after ÷ length before preparation. Measure width separately.
A sample does not guarantee whole-cut behavior. Squaring and matching are additional needs.
A prepared-fabric worked example
42 + 42 − ½ − ½ = 83 inches assembled. The red seam band is enlarged for clarity.
A 60 × 80 top, 4-inch edge allowance and 42 usable prepared inches need two 88-inch cuts with ½-inch seams.
That uses 176 prepared inches, about 4.89 yards, rounded to 5. It does not prove 5 yards bought before washing will remain enough.
This site does not prescribe one preparation method for every product. Follow the fabric’s instructions, consider the completed quilt’s care, and confirm the requirements of the person doing the quilting.
How much extra flannel should I buy?
The panel result is a starting point. Additional fabric depends on the specific product, planned preparation, usable width, print matching, and squaring needs. The calculator does not supply a universal percentage.
Can I use wide flannel without a seam?
Only if its prepared usable width covers at least one complete backing dimension. Check the actual product measurements with the wide-backing layout.
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