GPA Calculator mechanism

Model scope

The core formula is standard and mathematically valid, but the specification is not complete enough for an institution-independent implementation. Exact ambiguities requiring resolution are: which letter-grade mapping applies for each scale; what weighted means; whether repeated courses, pass/fail courses, withdrawals, plus/minus grades, and grade replacement are included; and what data defines cumulative versus semester GPA. The honest-label warning that grading scales vary by institution is required and should be prominent.

• The weighted-average formula is correct only when credit hours are the intended weighting factor and all credit hours use the same unit.
• The grade-point mapping is not specified; a 4.0, 5.0, or weighted scale can vary by institution.
• The meaning of the weighted scale is ambiguous: it could mean a different maximum scale, honors/AP bonus points, or another institution-specific rule.
• Cumulative GPA requires prior coursework or a prior GPA plus prior attempted credits, but the input specification only defines one course list.
• No rounding or precision policy is specified for displayed GPA values.

Units and conventions

• All credit hours must be expressed in one consistent unit before calculation; semester and quarter hours must not be mixed without conversion.
• Grade points are dimensionless and must come from the selected institution-specific scale.
• The test vectors explicitly provide their grade-point mappings; these mappings are assumptions, not universal standards.
• Zero-credit courses contribute zero to both the numerator and denominator and therefore do not affect GPA.
• A semester GPA is calculated from the courses in the supplied semester list; a cumulative GPA cannot be calculated without all relevant historical coursework or prior aggregate totals.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "scope": "semester",
    "scale": "4.0 standard for this test",
    "grade_point_mapping": {
      "A": 4,
      "B+": 3.3,
      "C": 2
    },
    "courses": [
      {
        "course": "Calculus I",
        "grade": "A",
        "credit_hours": 3
      },
      {
        "course": "English Composition",
        "grade": "B+",
        "credit_hours": 3
      },
      {
        "course": "Biology",
        "grade": "C",
        "credit_hours": 4
      }
    ]
  },
  "expected_outputs": {
    "gpa": 2.99
  },
  "working": "A: 4.0 × 3 = 12.0; B+: 3.3 × 3 = 9.9; C: 2.0 × 4 = 8.0. Weighted points = 12.0 + 9.9 + 8.0 = 29.9. Total credits = 3 + 3 + 4 = 10. GPA = 29.9 ÷ 10 = 2.99."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The zero-total-credit vector produces an undefined division and must be rejected. The specification also leaves scale tables and plus/minus conventions institution-specific, so accepting such inputs without an explicit configured table can produce materially different GPAs.

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
• BOUNDARY_HAZARD_CATALOG.json