How SawNest calculates a plan
The useful part of a calculator is not only its answer. It is knowing which inputs were used, which rules were applied, and where the model stops.
Measurements and precision
Imperial inputs accept decimals, simple fractions, and mixed numbers. Metric inputs accept decimal millimeters. The displayed plan rounds labels for readability while the calculation retains the entered decimal value.
Finished part sizes remain separate from blade kerf and stock-edge trim. This makes allowances visible and prevents a hidden adjustment from changing the dimension a finished part is supposed to have.
Sheet-layout heuristic
The flagship expands quantities into individual rectangles, sorts larger and more constrained parts first, and evaluates each allowed orientation against the remaining rectangles on every sheet. When a part is placed, the containing rectangle is split into two non-overlapping rectangular regions after kerf is removed.
The process is deterministic: the same valid inputs use the same sort and tie-break order. The result is labeled heuristic best-found. It is not represented as a mathematically proven optimum.
Linear-stock heuristic
The board planner uses best-fit decreasing. It sorts finished lengths from longest to shortest and places each one into the used board that leaves the smallest valid remainder, opening a new board when none fits.
Kerf is applied between adjacent finished pieces. A further blade width is deducted from a displayed reusable terminal offcut because that remainder must be separated from the final part.
Quality checks
Published calculator behavior is checked against deterministic examples for exact fits, kerf boundaries, impossible parts, trim, rotation, fractions, and repeated runs. Pages are also tested as server-rendered HTML so the purpose, method, and navigation remain available without waiting for the interactive code.
When a part cannot fit the entered stock in either permitted orientation, the tool reports it as unplaced rather than silently dropping or resizing it.
Limits and safety
SawNest does not see knots, voids, warp, sheet damage, blade runout, joinery allowance, sanding or milling loss, machine capacity, material support, kickback risk, structural suitability, or local building rules. It does not generate machine-operating instructions.
Verify actual stock, finished-versus-rough dimensions, trim, blade kerf, grain, defects, and every operation. Follow the tool manufacturer’s instructions and use appropriate guards, PPE, push devices, and work support.
Reference sources
Definitions and safety context are checked against primary sources where possible. Useful starting points include the OSHA table-saw guidance, APA plywood reference, and the USDA Forest Products Laboratory's Wood Handbook.
Those sources do not endorse this calculator. Product-specific dimensions and safe procedures should come from the stock supplier and tool manufacturer.