Public evidence

education.gpa_letter

Machine-checked verification for calculation version 1.1.2 · tier engine_tested

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Verification

16/16 calculation tests · Production surface contract 3/3

Golden tests 16 / 16
Boundary tests 0 / 0
Property tests 0 / 0
Production surface contract 3 / 3
Engine tested Yes
Source checked Yes
Artifact integrity PASS
Production attestation Embedded snapshot: STALE · Last attested schema matched 1.1.2 snapshot / local build · Semantic contract ✓ · Last attestation PASS · current evidence changed · re-attestation required · Public/cache ✓ · Origin ✓ · Live production status PASS (0 stale; 164 CURRENT) @ 2026-09-16T06:44:24.909Z
Semantic contract PASS
Evidence attested at 2026-09-16T06:44:24.203Z
Last production check 2026-09-16T06:44:24.203Z
Public / cache PASS
Origin PASS
Supplemental domain review Not performed
Named expert review Not performed

release artifacts aligned PASS
schema valid input executes PASS
schema rejects incomplete input PASS

Fingerprint sha256:78ffd7e2acbb2873491fbe410ff218b311b72d30c299cd1fba18642b74e1bb18

Input schema sha256:258a7b51431481323beae21596f2f06febf8da6cc157ffbfc895d2116fd58ec8 · Output schema sha256:5f6be44af76efeb83e06df0ae6e102fd28eb6104a3efeecb9cf92a4bb2b54748 · 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: 2026-09-15
Evidence core: 2026-09-15T06:31:46.555Z
Rendered: 2026-09-16T22:03:43.767Z
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

Published checks

Golden, boundary, and property cases included in this evidence build.

ID	Kind	Status	Detail
`nearest-3.67-a-minus`	golden	pass	Expected letter=A- · matchedGpa=3.67 · tie=false · Actual value=A- · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=3.67 · gpa=3.67
`nearest-3.50-tie-up-a-minus`	golden	pass	Expected letter=A- · tie=true · Actual value=A- · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=3.5 · gpa=3.5
`nearest-3.4999-b-plus`	golden	pass	Expected letter=B+ · tie=false · Actual value=B+ · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=3.4999 · gpa=3.4999
`nearest-3.5001-a-minus`	golden	pass	Expected letter=A- · tie=false · Actual value=A- · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=3.5001 · gpa=3.5001
`floor-3.50-b-plus`	golden	pass	Expected letter=B+ · tie=false · Actual value=B+ · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=floor · inputGpa=3.5 · gpa=3.5
`nearest-3.835-tie-up-a`	golden	pass	Expected letter=A · tie=true · Actual value=A · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=3.835 · gpa=3.835
`nearest-4.165-tie-up-a-plus`	golden	pass	Expected letter=A+ · tie=true · Actual value=A+ · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=4.165 · gpa=4.165
`nearest-3.33-b-plus`	golden	pass	Expected letter=B+ · matchedGpa=3.33 · tie=false · Actual value=B+ · status=ok · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=3.33 · gpa=3.33
`letter-b-plus-points`	golden	pass	Expected value=3.33 · letter=B+ · Actual value=3.33 · status=ok · mode=to-gpa · scale=plus-minus · scaleLabel=Plus/minus 4.33 · gpa=3.33 · normalized=false · letter=B+
`flat-3.50-tie-up-a`	golden	pass	Expected letter=A · tie=true · Actual value=A · status=ok · mode=to-letter · scale=flat · scaleLabel=Flat 4.0 · match=nearest · inputGpa=3.5 · gpa=3.5
`linear5-4.6-normalized-a-minus`	golden	pass	Expected letter=A- · gpa=3.68 · normalized=true · Actual value=A- · status=ok · mode=to-letter · scale=linear5 · scaleLabel=Linear 5.0 · match=nearest · inputGpa=4.6 · gpa=3.6799999999999997
`linear5-alias-weighted`	golden	pass	Expected scale=linear5 · letter=A- · Actual value=A- · status=ok · mode=to-letter · scale=linear5 · scaleLabel=Linear 5.0 · match=nearest · inputGpa=4.6 · gpa=3.6799999999999997
`negative-gpa-rejected`	golden	pass	Expected status=invalid · code=GPA_OUT_OF_RANGE · Actual status=invalid · code=GPA_OUT_OF_RANGE · message=GPA must be between 0 and 4.33 for this scale. · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=-2
`over-max-plus-minus-rejected`	golden	pass	Expected status=invalid · code=GPA_OUT_OF_RANGE · Actual status=invalid · code=GPA_OUT_OF_RANGE · message=GPA must be between 0 and 4.33 for this scale. · mode=to-letter · scale=plus-minus · scaleLabel=Plus/minus 4.33 · match=nearest · inputGpa=4.5
`over-max-flat-rejected`	golden	pass	Expected status=invalid · code=GPA_OUT_OF_RANGE · Actual status=invalid · code=GPA_OUT_OF_RANGE · message=GPA must be between 0 and 4.00 for this scale. · mode=to-letter · scale=flat · scaleLabel=Flat 4.0 · match=nearest · inputGpa=4.01
`over-max-linear5-rejected`	golden	pass	Expected status=invalid · code=GPA_OUT_OF_RANGE · Actual status=invalid · code=GPA_OUT_OF_RANGE · message=GPA must be between 0 and 5.00 for this scale. · mode=to-letter · scale=linear5 · scaleLabel=Linear 5.0 · match=nearest · inputGpa=5.1