GPA Scale Conversion
Overview
Korean universities grade on three incompatible maxima — 4.5, 4.3 and 4.0 — and the linear ratio conversion GPA_new = GPA_old ÷ Scale_old × Scale_new is the transformation most admissions offices and employers apply when comparing them. A 3.8 on the common 4.5 scale maps to 3.8 ÷ 4.5 × 4.3, or 3.63 on a 4.3 scale, and to 3.38 on a 4.0 scale. The method preserves relative standing but not grade-boundary meaning: an A on a 4.5 scale often begins at 4.0 while the same letter starts at 3.7 on a 4.3 scale, so a linear map can shift a student across a letter boundary. The World Education Services and similar credential evaluators therefore rebuild transcripts course by course from letter grades rather than rescaling a single cumulative figure.
Variables
| Symbol | Name | Unit | Description |
|---|---|---|---|
| $GPA_old$ | Source grade point average | points | The cumulative average on the originating scale. |
| $Scale_old$ | Source maximum | points | The highest attainable value on the originating scale (4.5, 4.3 or 4.0). |
| $Scale_new$ | Target maximum | points | The highest attainable value on the destination scale. |
Three Scales in One Country
Korean higher education never converged on a single grading maximum. Most universities award a highest grade of 4.5, a substantial minority use 4.3, and institutions modelled on United States practice use 4.0. Comparing transcripts therefore requires a mapping, and the one applied by most admissions offices and employers is a proportional rescaling:
$$GPA_{new} = \frac{GPA_{old}}{Scale_{old}} \times Scale_{new}$$
A 3.8 on a 4.5 scale becomes $3.8/4.5 \times 4.3 = 3.63$ on a 4.3 scale and 3.38 on a 4.0 scale.
What the Linear Map Preserves
The transformation preserves relative position: a student at 84% of their scale's maximum remains at 84% after conversion. That is the correct property for ranking applicants within a single institution's applicant pool, and it is why the method is widespread despite its known limitations.
What It Does Not Preserve
Grade boundaries do not sit at proportional positions. On a 4.5 scale an A often begins at 4.0, that is 88.9% of maximum; on a 4.3 scale it may begin at 3.7, or 86.0%. A converted figure can therefore fall on the opposite side of a letter boundary from the grade actually earned. Credential evaluators such as World Education Services avoid the problem by rebuilding the transcript course by course from letter grades and credit hours rather than rescaling one cumulative number.
Choosing a Method
| Purpose | Recommended approach |
|---|---|
| Internal ranking of a single cohort | Linear rescaling |
| Foreign graduate admissions | Course-by-course re-evaluation |
| Employer screening threshold | State the scale alongside the figure |
Derivation & History
The mapping is the unique linear transformation that fixes zero and maps the source maximum onto the target maximum, that is $f(x) = x \cdot (S_{new}/S_{old})$. Fixing zero is an assumption rather than a necessity: an alternative anchoring maps the passing threshold rather than the origin, which compresses the usable range and raises converted values. Because Korean scales share an approximately common passing grade near 2.0 on the 4.5 system, the origin-anchored map is the more conservative of the two and is the one most institutions adopted.
Worked Examples
4.5 scale to 4.0 scale
- Express as a proportion of maximum: 4.12 ÷ 4.5 = 0.9156
- Apply the target maximum: 0.9156 × 4.0 = 3.662
- Round to two decimals as transcripts require: 3.66
Result: 3.66 on a 4.0 scale
4.3 scale to 4.5 scale
- 3.55 ÷ 4.3 = 0.8256
- 0.8256 × 4.5 = 3.715
Result: 3.72 on a 4.5 scale
Edge Cases & Limitations
Scores above the stated maximum: Some departments award bonus points. The ratio should be capped at 1.0 before rescaling, otherwise the converted figure exceeds the target maximum.
Percentage-based transcripts: Chinese and Indian institutions frequently report percentages rather than points, and no single linear map converts them reliably; official conversion tables differ by institution.
Major versus cumulative average: Graduate admissions often weight the major GPA separately. Converting only the cumulative figure discards that distinction.
Pass/fail credits: Courses without a grade point are excluded from the average entirely and must not be counted as zero.
Real-World Applications
Graduate school applications, overseas employment screening, scholarship eligibility thresholds and exchange-programme placement all require a common scale. Korean public-sector hiring frequently sets a minimum cumulative average, which candidates from 4.3-scale institutions must convert before applying.