Public evidence

education.gpa_letter

Machine-checked verification for calculation version 1.1.3 · tier engine_tested

Open calculator API Capability Download JSON CVP Manifest MCP Review policy

CVP status

Approximate interpretation on plus/minus 4.33, flat 4.0, and linear 5.0 normalization

Declared partition coverage: PASS · 6/6 declared partitions (plus-minus-nearest, floor, flat, linear5, to-gpa, invalid-domain)
Versions: Calculation 1.1.3 · CVP protocol 1.0.0-proposed · Evidence 2026-10-28.meta-metrics-v2
Verification revision: 2026-10-28.meta-metrics-v2 · 2/2 property · digest bfc9ab36f236

Verification

Legacy regression suite: 16/16 calculation tests · Production surface contract 6/6

Three distinct suites: educational examples on the calculator page, this legacy regression count (16/16 golden + boundary), and the CVP verification suite below. They are not the same number. Property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the CVP Manifest . SKIP (0/0) means that suite has no published vectors.

This calculator CURRENT · Public schema 1.1.3 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

CVP verification suite

Protocol checks from the Evidence Manifest. Distinct from the legacy regression suite above. Verification revision 2026-10-28.meta-metrics-v2. Calculation version 1.1.3. CVP 1.0.0-proposed. 7/7 golden · 3/3 CVP boundary · 1/1 invalid · 2/2 property · 1/1 metamorphic · 1/1 cross-interface · 6/6 CVP contract. digest bfc9ab36f236.

Golden (oracle-backed) 7 / 7
CVP boundary 3 / 3
Invalid input 1 / 1
Property 2 / 2
Metamorphic 1 / 1
Cross-interface 1 / 1
CVP contract 6 / 6
Interfaces PASS · UI (SSR) / REST / MCP
Interface claim ui-ssr is query-result HTML, not a live browser session.
Assurance Core

release artifacts aligned PASS
schema output required declared PASS
schema valid input executes PASS
engine success output validates schema PASS
schema rejects incomplete input PASS
rest success payload validates schema PASS

Fingerprint sha256:000b22bd9b33392e932ecdbf31f9d8cde99d2049b58579e7bb5be50c5d3225ec

Input schema sha256:34264687c89f08e41986002cf356b752837057ce0446b8f0b7ea304add7f35e1 · Output schema sha256:c02b8c720af9be5cd7928b3e3b7c604acc217b0e65d935eef6fef983aa970c99 · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Build & scope

Engine identity and declared limitations.

Tool: gpa-to-letter
Engine: gpa-letter
Engine build: 2026-09-21
Evidence core: 2026-09-21T15:56:45.653Z
Rendered: 2026-11-10T05:18:42.044Z
Last reviewed: —

Assumptions

Default plus/minus map uses A+=4.33 … F=0.
Percentage ranges are one common U.S. syllabus convention for the matched letter, not a function of the input GPA.
Linear 5.0 assumes a 5.0 numeric ceiling linearly mapped to 4.0. It is not a generic weighted→unweighted GPA conversion.
Nearest matching is an approximation algorithm, not a registrar rule for converting cumulative GPA back into a letter.

Limitations

Interpretation of a numeric GPA or a single letter — not a registrar conversion
Not a term or cumulative GPA from a course list (use the GPA calculator)
Example percentage bands are syllabus conventions, not derived from GPA

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

University of Alabama — Grades and Grade Points — A+ = 4.33; A = 4.00; A− = 3.67; B+ = 3.33; … F = 0.00
Supports: Published plus/minus 4.33 grade-point map used as this calculator’s default reference model
Arizona State University Registrar — Grades and grading policies — A+ = 4.33 on the grading scale, but cumulative GPA is capped at 4.00
Supports: Same 4.33 letter points can still differ in how cumulative GPA is reported
Simon Fraser University SIAT — Recommended grading scale — A− = 85–89.5% with A− = 3.67 grade points (not 90–92%)
Supports: Percentage bands are school-specific even when grade points match 4.33 / 4.00 / 3.67
University of California Admissions — GPA requirement — A/B/C/D map to 4/3/2/1, then extra honors/AP/IB points are added with a honors-point cap
Supports: Why Linear 5.0 must not be described as a generic weighted→unweighted GPA conversion
Randolph College Physics — Grade Scale — A+ = 97–100; A = 93–96; A− = 90–92; B+ = 87–89; … D− = 60–62; F = 0–59
Supports: The example percentage-band table shown by this calculator (a published syllabus convention, not universal)
St. Olaf College — Typical Grading Scale (Jill Dietz) — 97–100% A/A+; 93–96% A; 90–92% A−; 87–89% B+; … 60–62% D−; <60% F
Supports: Independent published example of the same 97–100 / 93–96 / 90–92 syllabus convention

Verification disclosure

Aggregate outcomes, scope and artifact commitments are public. Complete test inputs, expected values, execution records and oracle infrastructure are retained privately. This summary does not independently reproduce the full verification run.