Quilt backing calculator
Make a panel plan from actual top dimensions, usable cloth width and deliberate allowances. Keep the numbers with the fabric.
Measure before entering
Measure the completed quilt top. Choose inches or centimetres and enter the extra backing needed on every edge. Use fabric width after excluded selvages and any preparation. Confirm your quilter’s size and seam instructions before comparing layouts.
Set the allowance on each joined edge, total extra cut length per panel, purchasing buffer and rounding increment. Both directions are compared unless you restrict the choice. Switching measurement units converts length inputs. The diagram is a schematic, not a cutting template.
Build the backing rectangle
Required backing width = top width + 2 × edge margin. Required backing length = top length + 2 × edge margin. Four inches on every edge of a 60 × 80 in top gives 68 × 88 in.
The margin enlarges the assembled rectangle. Extra cut length is separate and is added once to every panel length; two inches means two total for both ends.
Panels and joined coverage
For a required span D, usable fabric width F and allowance s on each joined edge: panel count N = max(1, ceil((D − 2s) ÷ (F − 2s))). F must exceed 2s. Joined span = N × F − 2s × (N − 1).
Vertical seams cover the backing width with panels cut along its length. Horizontal seams cover the backing length with panels cut across its width. The tool plans equal full-width panels; it does not optimize decorative inserts or offcuts.
Yardage and purchase rounding
Raw yardage = panel count × (required cut-direction dimension + extra cut length) ÷ 36, using inches. Purchasing requirement = raw yardage × (1 + buffer/100). Round that total upward to the selected ⅛, ¼, ½ or whole-yard increment.
One yard is 0.9144 m. The displayed metre length converts the rounded yard purchase; metric retailer increments need a separate upward rounding check. Compare allowed plans by rounded purchase, then raw length and panel count.
Two directions for the same top
A 60 × 80 in top with 4 in edge margins, 42 usable inches, ½ in allowances and 2 in total end room needs a 68 × 88 in back. Vertical: two 90 in cuts, 5 yd. Horizontal: three 70 in cuts, 5.833 yd raw, rounded to 6 yd at quarter-yard increments. Both examples use no purchasing buffer.
A print or quilter’s requirement can make the six-yard plan the correct one. Select the allowed direction before accepting a shopping recommendation.
A separate strip plan
Required binding length = 2 × (top width + top length) + extra ends/corners. For usable binding width U and loss j at each join, strip count = max(1, ceil((required length − j) ÷ (U − j))). U must exceed j.
Binding fabric yardage = strip count × strip cut width ÷ 36, then round upward to the same purchase increment. The backing percentage buffer is not applied to binding. Binding uses the top perimeter, not the larger backing perimeter. Straight-cut strips only; diagonal join loss is editable. Bias binding and reuse of backing surplus are excluded.
What the worksheet can compare
Compare ordinary-width fabric with measured wide backing, change the top after borders, check seam directions or make separate notes for several projects. See wide versus pieced backing and the illustrative yardage examples.
Verify the actual material
Dimensional ranges, expressed in inches: top 0.01–1000; margin and extra cut length 0–30; backing/binding usable width 1–300; seam allowance 0–2; binding strip width 0.1–10; binding join loss 0–10; extra binding length 0–100. Centimetre mode uses equivalent physical ranges. Purchasing buffer: 0–50%. Plans over 100 backing panels or 1000 binding strips are rejected.
These are software limits. Print repeats, width shrinkage, cloth defects, decorative piecing, material behavior, quilting clearance and shop cutting rules need your own check. Invalid inputs hide earlier results and disable copying. Measurements are not uploaded or saved.
Independent measurement context
Quilted Joy’s backing guide explains its service requirements. Hancock’s quilting information provides general measurement context. Their shortcuts and chart assumptions can differ from this explicit panel model. We are independent of these providers; ask your actual quilter for project-specific instructions.
Calculator questions
How much backing fabric do I need?
Enter the measured top, extra room on each edge and usable fabric width. The tool compares equal full-width panels after seam loss, adds cut-end allowance and rounds the shopping length upward.
What does usable fabric width mean?
The span you can use after excluded edges and any preparation. A nominal bolt width may include selvages and should not replace a dependable measurement.
Does the lowest yardage always give the right layout?
No. Print direction or your quilter’s seam instructions may require a particular orientation. Select that restriction before accepting the cut plan.
Are my measurements saved?
Calculations run in browser memory without uploads, cookies or a persistent history. Copying transfers a plain-text note to your device clipboard.
Is four inches on each edge a universal rule?
No. It is the initial example. Enter the margin your quilter or quilting method requires; four per edge adds eight to each dimension.
Does a purchasing allowance predict shrinkage?
No. It adds roll length, not width. Update the usable width after preparation and plan print matching separately.
Can binding come from my backing offcuts?
The estimate treats binding as a separate fabric purchase. Suitable offcuts can be used only after an actual strip cutting plan confirms their widths and lengths.
What does the diagram represent?
Panel orientation and the required backing outline. It is a schematic, not a pattern-matching or full-size cutting template.