SelvedgeBacking inputs and target dimensions
W/H are top width/length, E is extra per edge, F is usable fabric width, S is joining-edge allowance. Target backing = W + 2E by H + 2E. Confirm the required allowances with your quilter.
Full-width panel calculation
Let A span the joined panels and L be cut length. N panels span N × F − 2S × (N − 1). Minimum count = max(1, ceil((A − 2S) ÷ (F − 2S))), requiring F > 2S.
Yards = N × L ÷ 36. Purchase = ceil(yards × 4) ÷ 4. Tiny tolerances avoid extra cuts caused only by floating-point boundaries.
Choosing a direction and reading the diagram
Automatic selects lower exact yardage, preferring vertical on a tie. Manual selection keeps that direction. The diagram shows joined panels, target and excess.
The 60 × 80-inch worked calculation needs two 88-inch vertical cuts (buy 5 yards) or three 68-inch horizontal cuts (buy 5¾). These are teaching figures, separate from your project.
What the backing result excludes
Backing excludes preparation, matching, squaring, mistakes and shop-specific increments. Binding, batting and borders use separate tools. No diagonal-backing or remnant optimizer is included. See fabric choices.
Eight companion tools, eight explicit scopes
Each result covers its stated component. Lengths use inches; fabric purchases round to quarter yards where applicable.
| Calculator | Model and limit |
|---|---|
| Binding | Straight strips with diagonal joins. N strips of length F and width B yield N × F − (N − 1) × B joined inches. Adds your closing allowance; not continuous bias binding. |
| Bed quilt size | Mattress width + two drops; mattress length + one drop + head allowance. The same drop applies to sides and foot. Mattress presets are references, not fixed quilt sizes. |
| Border | One equal-width, straight border, sides first. Cut widths include two seams; joins consume two seam allowances. Each side has its own strips, without offcut reuse. |
| Plain-square fabric | Cut square = finished square + two seams. Squares per strip round down; required strip count rounds up. One fabric and repeated squares, not arbitrary patchwork. |
| Block grid | Finished ↔ unfinished dimensions differ by two seam allowances. A rectangular grid joins complete blocks directly; no sashing or internal block-piece calculation. |
| Hexagons | Exact whole-piece count in staggered flat-top columns. Calculates the irregular layout’s bounds and a perpendicular seam offset, not fabric yardage or a fully covered rectangle. |
| Batting | Adds the edge allowance, then compares single-piece roll cuts. No joined batting calculation; fit requires one complete target dimension across the usable roll width. |
| Pricing | Materials + labor + overhead, with fees and either margin or markup. Uses your assumptions; no fetched rates, market appraisal or profit guarantee. |
Validation and saved work
Backing limits: dimensions ≤1,000 inches, extra 0–50 per edge, joining allowance above 0 through 2 inches, and ≤1,000 panels. Companion tools report their own limits.
Input changes clear results until recalculation. Companion tools save separately; regular/wide backing share one project.
Browser storage can be lost. CSV and print are records, not importable backups. See the tool index.