Minimum Batch Size Planner methodology

unitContribution = selling price per unit − variable cost per unit

minimumUnits = ceiling((batch setup cost + target batch contribution) / positive unit contribution)

contributionAtMinimum = minimum units × unit contribution − batch setup cost

Money inputs and outputs use the currency selected in the scenario without changing the canonical methodology. Rates, margins, utilisation and buffers are entered as percentages and converted to decimal values for calculation.

• All inputs must be finite and remain inside the visible non-negative validation boundaries.
• Capacity and demand fields that represent physical units reject fractional values where the engine requires whole units.
• Rates remain inside the closed range from 0% to 100%.
• Unreachable contribution, crossover or payback thresholds return an explicit unavailable state rather than Infinity.
• Option comparisons reject an infeasible option when its entered capacity is below the required workload.

Batch setup cost minimum

setupCost ≥ 0 currency units/batch, ex tax — A lower value is rejected before calculation.

Batch setup cost maximum

setupCost ≤ 10,000,000 currency units/batch, ex tax — A higher value is rejected before calculation.

Selling price per unit minimum

unitSellingPrice ≥ 0 currency units/unit, ex tax — A lower value is rejected before calculation.

Selling price per unit maximum

unitSellingPrice ≤ 10,000,000 currency units/unit, ex tax — A higher value is rejected before calculation.

Variable cost per unit minimum

unitVariableCost ≥ 0 currency units/unit, ex tax — A lower value is rejected before calculation.

Variable cost per unit maximum

unitVariableCost ≤ 10,000,000 currency units/unit, ex tax — A higher value is rejected before calculation.

Target batch contribution minimum

targetBatchContribution ≥ 0 currency units/batch, ex tax — A lower value is rejected before calculation.

Target batch contribution maximum

targetBatchContribution ≤ 10,000,000 currency units/batch, ex tax — A higher value is rejected before calculation.

Maximum batch capacity minimum

maximumCapacityUnits ≥ 0 units/batch — A lower value is rejected before calculation.

Maximum batch capacity maximum

maximumCapacityUnits ≤ 100,000,000 units/batch — A higher value is rejected before calculation.

• All operating volumes, rates, workload, capacity, time, cost and contribution values are supplied by the user.
• Money inputs use one consistent ex-tax basis and every record refers to the same operating period.
• Demand realisation, recovery, hours saved and expected unit rates are scenarios, not forecasts or benchmarks.
• Committed sunk cost is disclosed but excluded from make, buy, outsource and hire incremental economics.
• The shared engine retains raw precision and display formatting never feeds back into calculation.

This planner has no current policy-data dependency. Its commercial assumptions are user supplied. Registered family-level regression suites exercise the shared business-logic engine and worked-result reconciliation.

• Results depend on complete and comparable incremental cost, capacity and operating records.
• The model does not forecast demand, service quality, employee performance, supplier reliability or disruption duration.
• A positive result or short payback does not establish implementation feasibility or guarantee a commercial outcome.
• The planner does not replace operational, accounting, tax, legal or financial advice.

This is educational decision support, not tax, accounting, legal or financial advice. Check the treatment of your actual transactions under the rules that apply to your business and seek qualified advice where appropriate.

Registered family-level suites test formula invariants and example reconciliation; the release ledger records that coverage without claiming a separate oracle for every line of public copy. There is no official threshold or benchmark to refresh for this planner. Commercial inputs remain user-supplied because they vary by business and contract.

1. 2026-07-31: Initial public release of the planner and methodology after pre-launch calculation, content, source and interaction review.