How HSC subjects are scaled in 2026 (and what it means for your ATAR)

Why scaling exists

Students take different combinations of courses, and a mark of 80 means different things in different courses. To add marks from different courses into one aggregate, UAC first puts them on a common scale. UAC's view is that scaling means you are neither advantaged nor disadvantaged by the courses you choose.

How UAC scales, step by step

From UAC's Report on the Scaling of the 2025 NSW HSC:

1. Raw marks. For each course UAC uses raw marks: your school assessment mark (moderated by NESA using the raw exam marks) and your raw exam mark. It does not scale the HSC marks on your results notice.
2. Standardisation. Marks in each course are standardised to a mean of 25 and standard deviation of 12 on a 1-unit basis.
3. Scaled means and spreads. UAC's model sets a course's scaled mean equal to the average academic achievement of its students, measured by their average scaled mark across all their courses. Solving this for every course at once gives the scaled mean of each 2-unit course. Its scaled standard deviation reflects the spread of overall achievement among its students.
4. Extension courses. Scaled means for extension courses come from how the extension students performed in the related 2-unit course. Mathematics Extension 2 is based on those students' performance in Mathematics Extension 1, and English Extension 2 on their performance in English Advanced. History Extension and Science Extension use weighted averages across the related 2-unit courses.
5. Maximum marks. In 2025 the maximum scaled mark in a course was the smaller of 50 and the scaled mean plus 2.46 times its initial scaled standard deviation.
6. Individual marks. A non-linear transformation converts each raw mark to a scaled mark between 0 and 50 that preserves the course's scaled mean and spread.

What the 2025 numbers show

Scaled means per unit (out of 50) for some large courses in 2025:

The average scaled mark across all HSC students is about 25 per unit, which is why scaled marks usually look lower than HSC marks.

What the means don't tell you

• Your position matters more than the course. In 2025 a 90th-percentile Biology student scaled to 39.9, well above a median Chemistry student (33.9).
• The bottom of a strong course still scales low. A bottom-quarter Mathematics Advanced student (25.9 or less in 2025) scaled below a 75th-percentile Mathematics Standard 2 student (31.5).
• Numbers move each year. Scaling is recalculated from each year's results, and small courses can move a lot.
• There's no HSC-mark-to-scaled-mark table. UAC says Table A3 of its report shows relativities between courses and shouldn't be used as a conversion table.

English

Your aggregate always includes your best 2 units of English. In 2025, English Advanced had a scaled mean of 32.8 and English Standard 20.4. That gap reflects the different cohorts. If you can do well in Advanced, the higher-scaled cohort helps; if you'd struggle, a strong Standard result may serve you better.

Practical advice

1. Start with university prerequisites and assumed knowledge.
2. Estimate where you'd finish in each course using Year 11 results and teacher advice.
3. Consider an extension course if you're strong in the 2-unit course: extension students are measured against their own performance in the parent course.
4. Keep a spare unit or two so a weaker result can drop out of your best 10.

For the full ATAR calculation, see how the HSC ATAR is calculated. For the complete ranking, see highest scaling HSC subjects.