High School GPA Rank Calculator

Overview

The High School Grade Calculator turns the raw score, class average, and standard deviation on a Korean report card into a Z-score, rank percentile, estimated class rank, relative grade tier, and absolute achievement level (A–E). It supports both the 5-tier system used by students who entered high school from 2025 and the 9-tier system for earlier cohorts, showing each alongside the other.

Formula

Z-score = (Raw Score − Class Average) ÷ Standard Deviation
Rank Percentile (%) = (1 − Φ(Z)) × 100
Estimated Rank = Class Size × Rank Percentile
Grade Cutoff Score = Average + Φ⁻¹(1 − cumulative ratio) × Standard Deviation

[5-tier, 2025 entrants onward] Tier 1 ≤10% · 2 ≤34% · 3 ≤66% · 4 ≤90% · 5 ≤100%
[9-tier, 2024 and earlier] Tier 1 ≤4% · 2 ≤11% · 3 ≤23% · 4 ≤40% · 5 ≤60% · 6 ≤77% · 7 ≤89% · 8 ≤96% · 9 ≤100%
[Achievement] A ≥90 · B ≥80 · C ≥70 · D ≥60 · E <60

How to Use

1. 1Choose the grading system: 5-tier for current 1st and 2nd year students, 9-tier for 3rd year.
2. 2Enter your raw score for the subject.
3. 3Enter the class average and standard deviation printed on your report card.
4. 4Enter the number of students enrolled in that subject.
5. 5Read your grade tier, achievement level, cutoff scores, and the points needed for the next tier.

Examples

Background

Korean high school grade tiers are relative to everyone enrolled in the same subject. Report cards print the raw score together with the class average and standard deviation, and those three numbers give a Z-score that locates a student within the distribution. From the 2025 entering cohort, the relative scale changed from nine tiers to five, widening the top band from 4% to 10%, while earlier cohorts keep the nine-tier scale. School records also carry an absolute achievement level (A–E) based on the raw score alone, which comprehensive-review admissions weigh alongside course difficulty. Results assume a normal distribution, so subjects with skewed score distributions will deviate.

Tips

• ✔Pick the right system: current 1st and 2nd year students are on 5 tiers, 3rd year on 9 tiers.
• ✔In subjects with a small standard deviation, one or two points can change your tier.
• ✔Electives with few students have tiny top bands — check the rank cutoffs before enrolling.
• ✔This is a normal-distribution estimate; heavy ties or score clustering will shift the real result.

FAQ