Break-Even Units Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-248

Effect

Computation or source lookup only

Input and validation requirements

The calculator can encounter an undefined division when price equals variable cost and should reject nonpositive contribution margins. The specified outputs also include margin of safety, but no actual-sales input is supplied, so that output is undefined for every test vector.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "fixed_costs": 12000,
    "price_per_unit": 50,
    "variable_cost_per_unit": 30,
    "actual_units": 800,
    "currency": "USD"
  },
  "expected_outputs": {
    "breakeven_units_raw": 600,
    "breakeven_units_required": 600,
    "breakeven_revenue": 30000,
    "margin_of_safety_units": 200,
    "margin_of_safety_revenue": 10000,
    "margin_of_safety_percent": 0.25
  },
  "working": "Contribution margin per unit = 50 - 30 = 20 USD/unit. Raw break-even units = 12000 / 20 = 600 units. Required whole units = ceiling(600) = 600 units. Break-even revenue = 600 * 50 = 30000 USD. Actual revenue = 800 * 50 = 40000 USD. Margin of safety units = 800 - 600 = 200 units. Margin of safety revenue = 40000 - 30000 = 10000 USD. Margin of safety percentage = 10000 / 40000 = 0.25 = 25%."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json