Burn Rate & Runway 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

t5-008

Effect

Computation or source lookup only

Input and validation requirements

The instrument reaches an undefined division-by-zero result when monthly expenses equal monthly revenue, and its raw formula produces negative runway values for cash-generating cases. Without explicit handling, the UI can show an invalid or misleading runway and zero-cash date.

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": {
    "cash_balance": 180000,
    "monthly_revenue": 20000,
    "monthly_expenses": 50000
  },
  "expected_outputs": {
    "net_burn_per_month": 30000,
    "runway_months": 6,
    "zero_cash_date": null
  },
  "working": "burn = 50,000 - 20,000 = 30,000 currency units/month. runway = 180,000 / 30,000 = 6 months. A zero-cash date cannot be computed because the spec provides no as-of date or date-conversion rule."
}

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-tranche5/tranche5-results.json