Margin vs Markup Converter

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-4

Evidence ID

t4-259

Ledger rows

1

No ledger note is attached.

Review findings

The core formulas pass standard mathematical verification, but the instrument needs explicit inverse formulas, input-selection rules, percentage representation, and domain validation before release. 'Price suggestion' should be labeled as a calculated price, not individualized pricing or financial advice; the existing educational-only label is appropriate.

Formula and scope findings

• The stated forward formulas are standard and correct: margin=(price-cost)/price and markup=(price-cost)/cost.
• The specification does not provide the inverse formulas needed for bidirectional conversion. Required inverses include: price=cost/(1-margin), markup=margin/(1-margin), price=cost*(1+markup), and cost=price/(1+markup).
• The output description 'the missing values, price suggestion' is ambiguous about which inputs are optional and which values must be returned.

Unit assumptions

• Cost and price must use the same currency and unit basis, such as both USD per item; mixing total cost with per-unit price is invalid.
• The test vectors interpret margin_percent and markup_percent as percentage points, so 20 means 20% and is converted to 0.20 before calculation.
• The formulas require price != 0 for margin and cost != 0 for markup.
• For ordinary positive cost and price, margin is below 100%; margin=100% causes price=cost/(1-margin) to divide by zero.
• Markup and margin are dimensionless ratios, reported as percentages only for display.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

A zero cost makes markup undefined, and an unlabelled margin value such as 50 is ambiguous between 50% and decimal 50. The converter should reject zero denominators and enforce explicit percentage units.

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": {
    "cost": 80,
    "price": 100,
    "currency": "USD",
    "basis": "per item"
  },
  "expected_outputs": {
    "margin_percent": 20,
    "markup_percent": 25
  },
  "working": "margin=(price-cost)/price=(100-80)/100=20/100=0.20=20%. markup=(price-cost)/cost=(100-80)/80=20/80=0.25=25%."
}

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-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json