Debt-to-Income Ratio Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Finance, Economics & Business (educational only — never individualized investment, tax, or legal advice)

Tranche

tranche-5

Evidence ID

t5-217

Ledger rows

1

No ledger note is attached.

Review findings

The core ratio is standard when all inputs are monthly and gross income is pre-tax. The exact ambiguity requiring review is the undefined composition of total monthly debt payments and the unspecified behavior for zero income. Retain the educational-only label and explicitly state that lender definitions, thresholds, and underwriting decisions vary.

Formula and scope findings

• The ratio formula is correct for monthly debt payments divided by gross monthly income, but the stated formula omits the multiplication by 100 required when the output is labeled as a percentage: DTI%=total_monthly_debt_payments/gross_monthly_income×100.
• The specification does not define which obligations must be included in total monthly debt payments, such as housing, installment loans, credit-card minimums, leases, alimony, or other recurring obligations.
• The 36%/43% lender-threshold note is not a computed formula and must be presented as illustrative only, because applicable underwriting thresholds and definitions vary by lender and loan program.

Unit assumptions

• Every debt-payment list element is a positive monetary amount in the same currency and monthly period.
• Gross monthly income is pre-tax income, expressed in the same currency and monthly period as the debt payments.
• If income is supplied from an annual figure, it must first be divided by 12; annual income must not be divided directly into monthly debt payments.
• DTI percentage is calculated as (sum of monthly debt payments ÷ gross monthly income) × 100.
• The illustrative 36% and 43% figures are percentages, not decimal ratios, and are not universal lending rules.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

A zero gross monthly income produces an undefined division; an implementation that does not reject it may expose Infinity or an invalid DTI percentage.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "monthly_debt_payments": [
      1500,
      300,
      200
    ],
    "gross_monthly_income": 5000
  },
  "expected_outputs": {
    "total_monthly_debt_payments": 2000,
    "dti_percent": 40,
    "threshold_note": "Illustrative reference only: 36% and 43%; actual lender criteria vary."
  },
  "working": "1. Sum debt payments: 1,500 + 300 + 200 = 2,000. 2. Divide by gross monthly income: 2,000 ÷ 5,000 = 0.40. 3. Convert to a percentage: 0.40 × 100 = 40%. 4. Result: DTI = 40%."
}

Related workflows

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json