Units and dimensions

  • All calculations use millimetres internally with exact conversion constants.
  • Usable WOF means fabric remaining after selvages; the editable default is 40 inches.
  • Finished rectangle dimensions gain seam allowance on both opposite edges. Cut dimensions do not.
  • Piece-level orientation and rotation choices override fabric defaults.

Fabric recommendations

Calculators first determine the layout or construction length, then add the selected safety allowance. Purchase length always rounds upward to the selected shop increment—never to the nearest increment or down.

Backing compares every valid panel direction and reports the lowest-yardage candidate without claiming it is always aesthetically preferable. Borders and sashing deduct fabric consumed by joins before counting WOF capacity.

Cutting planner priorities

  1. Produce a valid plan that accounts for every requested piece exactly once.
  2. Prefer practical strip-based cutting.
  3. Prefer less fabric length, then lower cut complexity.
  4. Use stable tie-breaks so identical inputs produce identical output.

Large valid inputs use a simpler grouped heuristic with a visible warning so browser work stays bounded. The diagram projects the chosen optimizer placements; it does not calculate a second layout.

Testing and source conventions

Automated golden fixtures and invariants cover conversions, placement bounds, non-overlap, orientation, purchase bounds, determinism, backing coverage, HST yields, and joined-strip capacity. Conventions that vary in practice remain editable and are described as defaults.

These practical references inform convention review; QuiltClarity's locked, test-backed calculation contracts control the actual implementation.