How this calculation works
Use a descending-length first-fit heuristic. Each piece goes into the first opened board with enough remaining length; otherwise open a new board. After a cut, remove the entered kerf, capped by the remaining sliver. A piece taking the exact remainder needs no further cut allowance.
Sort pieces descending; first-fit into usable stock; deduct separating kerf from the remainderA worked example
Two 1.2 m pieces and two 0.6 m pieces fit two 2.4 m boards at 3 mm kerf. Each board takes 1.2 m and 0.6 m, leaving 0.594 m after two cuts.
Good to know
A geometric material-planning estimate from the entered measurements. Check actual product dimensions and the project layout. No structural suitability, installation specification, local requirements, labor, tax or pricing is determined. Decimal input lists allow up to 6 places and at most 100 entries/rows, each no greater than 1,000,000. The displayed feasible allocation is a heuristic, not a proven minimum-stock result or a cutting safety plan. It ignores mitre geometry, defects, grain, joining and existing offcuts. End trim is a total allowance per board.
Reference: Google OR-Tools: bin-packing problem and capacity constraints (opens in a new tab) ↗
Total finished length is only a lower bound on stock needs
Three requested pieces of 1.3 m total 3.9 m. Dividing by 2.4 m stock and rounding up suggests two boards, but no board can contain two of those pieces. Without joining, three boards are needed even before considering cuts.
This planner sorts pieces from longest to shortest and puts each into the first existing board that can hold it. If none can, it opens another board. That first-fit plan is a useful explicit allocation, but it is not a proof that no better arrangement exists.
Original item numbers remain in the table even though processing order changes. This lets you reconcile every requested piece with the plan rather than losing the identity of repeated lengths.
Account for trim, saw loss and offcuts separately
End trim is a total allowance removed from every purchased board. Saw kerf is the width lost to a separating cut. A piece that uses the exact remaining usable length needs no further cut allowance; otherwise kerf is taken from the remainder and capped by that remainder.
The material-balance step checks purchased stock against finished pieces, end trim, modeled kerf and remaining offcuts. Offcuts are not automatically reusable stock for another job, and their total length cannot be treated as one continuous board.
Use the length converter before entering measurements from mixed unit systems. This model allocates straight lengths only; mitres, damaged ends, grain requirements, joining and real cutting procedures need a project-specific layout.
A few questions, answered
Is the displayed board count guaranteed minimal?
No. It is a feasible descending-length first-fit allocation, not an exact optimization result.
Can I join two offcuts for a long run?
Joining is not modeled. Every requested finished piece must fit one usable board.
Can I enter existing offcuts as stock?
This version assumes all purchased boards share one length. It does not mix an existing offcut inventory with new stock.