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HSC scaling is how the Technical Committee on Scaling, working through the Universities Admissions Centre (UAC), adjusts your HSC marks so a mark in one subject can be fairly compared with a mark in another before your ATAR is worked out. It exists because a mark of 80 in one course and a mark of 80 in another do not represent the same standard of competition, and the UAC scaling report is the only place that shows exactly how each subject scaled last year.
HSC scaling is the process that converts your raw HSC marks into scaled marks before they are added together to calculate your ATAR. NESA reports your HSC mark using your exam result and your moderated school assessment mark, but that HSC mark is not what universities compare you on. The Technical Committee on Scaling, a body that acts on behalf of the NSW Vice-Chancellors’ Committee, takes the raw marks behind your HSC result and scales them so that a student’s position can be compared fairly across completely different subjects.
Think of it the way Matrix teachers have long explained it to students: your HSC mark is like an amount in a foreign currency. It has to be converted before it means anything next to a mark earned in a different subject. The scaled mark is that conversion, and it is the number used to rank you against every other HSC student in the state.
NESA sets and marks the exams and reports your HSC mark and band. UAC’s Technical Committee on Scaling then scales the raw marks behind that result, and UAC sends you your ATAR once the calculation is finished.
The preface to the 2025 scaling report states this plainly: “the NSW Education Standards Authority (NESA) provides the HSC data from which the ATARs are calculated and the Universities Admissions Centre (UAC) advises individual students of their ATARs.” NESA never scales anything. Its job stops at your HSC mark. Scaling is a separate, later step, and it is the step that decides your ATAR.
A subject scales higher when the students who take it are, as a group, stronger performers across their other subjects, and your position within that group’s mark distribution decides your own scaled mark.
Scaling reflects the academic strength of the students sitting the exam with you, rather than how hard the subject is to learn. The 2025 report gives a clean worked example. At the 90th percentile of their own subject, a Chemistry student, a Design and Technology student, an Economics student, a Physics student and a Study of Religion II student were all ranked in roughly the same position relative to their peers.
| Subject (P90 result) | HSC mark per unit | Scaled mark |
|---|---|---|
| Chemistry | 45.0 | 43.6 |
| Economics | 45.5 | 43.0 |
| Physics | 45.5 | 43.0 |
| Studies of Religion II | 45.0 | 40.5 |
| Design and Technology | 45.0 | 37.1 |
Source: Report on the Scaling of the 2025 NSW HSC, Table 6.5. Marks are shown on UAC’s own per unit scale, where the course maximum sits near 50, not the 0-100 mark on your HSC results.
All five students sat in the same position in their own subject, yet they came away with five different scaled marks. Chemistry scaled highest because its candidature, as a whole, is the strongest. Design and Technology scaled lowest because its candidature is more mixed. None of this reflects how hard each exam paper was to sit.
Extension subjects and the sciences carried the highest scaled marks in 2025, while the two-unit subjects with the largest and broadest candidatures, including English Standard, scaled lowest.
UAC publishes a scaled mean for every course, which is the best single figure for comparing subjects against each other. The table below uses the 2025 figures for the most commonly chosen HSC subjects, again on UAC’s own per-unit scale.
| Subject | Candidature (2025) | Scaled mean | Median scaled mark (P50) |
|---|---|---|---|
| Mathematics Extension 2 | 3,844 | 43.4 | 44.7 |
| Mathematics Extension 1 | 9,279 | 39.7 | 41.5 |
| English Extension 1 | 3,691 | 36.1 | 36.9 |
| English Extension 2 | 1,423 | 35.8 | 36.5 |
| Chemistry | 10,369 | 32.0 | 33.9 |
| English Advanced | 26,292 | 32.8 | 33.7 |
| Mathematics Advanced | 16,809 | 31.9 | 33.2 |
| Economics | 5,741 | 31.4 | 33.0 |
| Physics | 8,817 | 31.0 | 32.2 |
| Biology | 20,710 | 26.2 | 26.7 |
| Legal Studies | 10,080 | 25.3 | 25.9 |
| Modern History | 10,953 | 25.0 | 25.8 |
| Business Studies | 20,452 | 23.9 | 23.4 |
| Mathematics Standard 2 | 31,762 | 23.3 | 23.2 |
| Ancient History | 7,495 | 22.4 | 22.5 |
| English Standard | 33,651 | 20.4 | 20.0 |
Source: Report on the Scaling of the 2025 NSW HSC, Table A3. This is the report’s own aggregation scale, per unit, with a course maximum near 50. It is not the 0-100 mark shown on a student’s HSC Record of Achievement, and it should not be read as a conversion table between the two.
Extension Mathematics and Extension English sit well above every 2-unit subject on this list, which matches what Matrix teachers see every year: a smaller, self-selecting candidature of students who have already chosen to go further than the standard course produces a consistently strong scaled result. Individual Extension students still finish anywhere across the distribution. What scales is the strength of the group they are competing against.
The comparison holds even across candidature size. Mathematics Extension 2 had 3,844 students sitting it in 2025, a fraction of the 16,809 who sat Mathematics Advanced. A student at the median of that smaller Extension 2 cohort still scaled 44.7, higher than a Mathematics Advanced student at the 90th percentile of the much larger Advanced cohort, who scaled 42.9. What decides the scaling is the academic strength of the candidature, not its size.
Understanding how your subjects scale is one input into a strong ATAR. Sitting well inside your own subject’s distribution is the other, and it is the one you actually control. Matrix’s HSC Exam Preparation course runs structured trial exam revision for Year 12 English and science students, built around the Matrix HSC Trial Preparation Book, mock trial exams written by HSC teachers, and 24/7 support from Ask Max.
English and science HSC Exam Preparation classes run from 20 July to 20 September. Maths Advanced, Extension 1 and Extension 2 classes are available online from 18 May. Places are capped at 15 students per class.
Yes. The 2025 scaling report shows students with identical average HSC marks per unit finishing with ATARs 20 points apart, because their subject choices put them in front of unequal competition.
The report’s own example is the clearest illustration of this. Two students, given the names Liam and Kellie, each averaged exactly 40.0 marks per unit across their five HSC subjects, both sitting at the 50th percentile within every one of their own courses.
| Liam | Kellie | |
|---|---|---|
| Subjects | Chinese Beginners, Drama, English Standard, Information and Digital Technology, Music 1 | Biology, Economics, English Advanced, French Continuers, Mathematics Advanced |
| Average HSC mark per unit | 40.0 | 40.0 |
| Average scaled mean across subjects | 21.9 | 31.3 |
| ATAR | 60.00 | 80.00 |
Source: Report on the Scaling of the 2025 NSW HSC, Table 6.1.
Liam and Kellie performed identically well inside their own subjects. The 20 point gap in their ATARs comes entirely from the strength of the students they were ranked against. This is the single most common source of confusion the UAC ATAR Enquiry Centre hears every results season, and it is exactly why a subject’s scaling matters at the point you choose it, not after the exam.
No. Choose subjects you can perform strongly in, then let scaling tell you what percentile you need to reach in that subject to hit your target scaled mark.
Matrix’s own subject selection guidance has held for years and the 2025 data does not change it. A subject that scales well does nothing for a student who finishes in the bottom half of its candidature. The English Advanced student sitting at the 25th percentile in 2025 still scaled 27.7, which beats the median English Standard result of 20.0 outright. The reverse holds too: a struggling Extension 2 Mathematics student can be outscored by a strong Mathematics Advanced student in the same cohort. Ask yourself four questions before you finalise your HSC pattern of study.
| Question | Why it matters |
|---|---|
| Do you find the subject genuinely interesting? | Motivation carries you through two years of content. Scaling cannot fix disengagement. |
| Do you understand what the subject actually involves at Year 11 and 12 level, not just the junior version? | Chemistry and Physics are a different discipline to the Stage 5 science that leads into them. |
| Does a university course you are aiming for require or recommend it? | A prerequisite you skip cannot be recovered with a better scaled mark elsewhere. |
| Can you realistically finish in the upper half of that subject’s candidature? | A subject’s scaled mean only helps the students who are competitive within it. |
| Mistake | The fix |
|---|---|
| Dropping a subject you are strong in because “it doesn’t scale well” | Check where you sit in the candidature, not just the subject’s scaled mean. A strong position in a moderate subject often beats a weak position in a highly scaled one. |
| Assuming a subject is “scaled down” every year on principle | Scaling is recalculated from the current year’s candidature every year. The 2025 report confirms no course is scaled on a fixed formula. |
| Comparing HSC marks across subjects as if they were on the same scale | A mark of 80 in English Standard and a mark of 80 in English Advanced sit at different percentiles of their own candidatures. Compare positions, not raw marks. |
| Treating your predicted ATAR as fixed once trials are done | Your final scaled mark depends on the whole HSC candidature sitting each exam with you, which is not settled until after the HSC. |
| Believing your school or postcode affects your scaled marks | UAC states plainly that neither factor is used anywhere in the ATAR calculation. |
Scaling is the middle step. NESA marks your exams and reports your HSC result, then scaling adjusts the raw marks behind that result. Your scaled marks are added into an aggregate, and that aggregate becomes your ATAR.
| Guide | What it covers |
|---|---|
| Part 1: How HSC Marks Are Calculated | How NESA combines your exam mark and school assessment into your HSC mark |
| Part 2: HSC Scaling (this guide) | How your raw marks are scaled before they are aggregated |
| Part 3: How Your ATAR Is Calculated | How your scaled marks become your final ATAR |
| Part 4: How to Maximise Your ATAR | Practical subject and study strategy once you understand scaling |
| Part 5: HSC Tips from 99+ ATAR Students | What actually worked for students who reached the top band |
You can read the whole guide from the beginner’s guide to ATAR scaling overview, or use the Matrix ATAR calculator to see how your own predicted marks translate into an estimated ATAR.
“Most of the students who get caught out by scaling didn’t choose an unusual subject,” says the Matrix HSC English and Maths faculty. “They chose the right subject for the wrong reason, then eased off once they assumed the scaling would carry them. It won’t. You still have to earn the position inside the subject.”
No. UAC’s 2025 scaling report states that the ATAR calculation uses only the marks NESA provides and nothing else. Your school, campus or postcode play no part in how your marks are scaled.
No. Scaling is carried out fresh each year from that year’s candidature. If the academic strength of the students taking a subject changes, its scaled mean changes with it. A subject that scaled comparatively low in 2025 is not locked into scaling low in 2026 or 2027.
No. Your scaled mark depends on where you sit within that subject’s candidature, not on the subject’s scaled mean alone. A student in the bottom quarter of a highly scaled subject can still be outscored by a student in the top quarter of a more moderately scaled one.
Your scaled marks from your best 10 units, including your best 2 units of English, are added into an aggregate. That aggregate is then converted into a percentile rank against your entire age group in NSW, which becomes your ATAR. Part 3 of this guide walks through that final step.
UAC publishes the full Report on the Scaling of the 2025 NSW HSC as a free PDF, including every subject’s candidature size, scaled mean and percentile breakdown. It is the primary source behind every figure in this guide.
Generally, no. A subject’s scaled mean only benefits students who are performing competitively within it. If you are consistently in the bottom of a subject’s candidature, a moderately scaled subject you can genuinely succeed in will usually produce a better scaled mark than a highly scaled subject you are struggling to pass.
Choosing the right subject is one decision. Where you land inside that subject’s candidature is the one you keep making every week of Year 11 and 12.
Matrix’s structured HSC courses build the exam technique and content mastery that decide where you finish inside your subject’s candidature, across English, Maths, Biology, Chemistry and Physics.
On campus at all seven NSW campuses, or online through Matrix+. First Lesson Money-Back Guarantee.
Matrix Education is the leading tutoring college for Year 3 to 12 students. Read the next chapter in this series, Part 3: How Your ATAR Is Calculated, to see how your scaled marks become your final rank.
Written by Matrix Education
Matrix is Sydney's No.1 High School Tuition provider. Come read our blog regularly for study hacks, subject breakdowns, and all the other academic insights you need.
© Matrix Education and www.matrix.edu.au, 2025. Unauthorised use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Matrix Education and www.matrix.edu.au with appropriate and specific direction to the original content.
