How Does HSC Scaling Work?
HSC scaling adjusts raw exam marks so that students are ranked fairly across subjects with different difficulty levels. Here is exactly how it works.
The four-step process
- You sit your HSC exams and receive a raw mark out of the total available marks.
- NESA aligns your mark to account for differences in how your school assessed you internally (school assessment marks are moderated against your cohort’s external HSC performance).
- UAC scales your aligned mark using the academic performance of students who sat multiple subjects. A subject attempted by high-performing students tends to scale up; one taken mainly by lower-performing students may scale down.
- Your best 10 units are selected (including at least 2 units of English), added together, divided by the maximum possible aggregate, and compared against all eligible students to produce your ATAR percentile rank.
Which subjects scale up and which scale down?
| Subject | Direction | Example: raw 80 scales to approx. |
|---|---|---|
| Maths Extension 2 | Scales up strongly | ~91 |
| Maths Extension 1 | Scales up moderately | ~87 |
| Physics | Scales up slightly | ~84 |
| Chemistry | Scales up slightly | ~83 |
| Maths Advanced | Roughly neutral | ~82 |
| English Advanced | Scales down slightly | ~77 |
Approximate values based on historical UAC data. Actual scaling shifts each year with cohort performance.
Frequently asked questions about HSC scaling
Does scaling mean I should always choose hard subjects?
Not automatically. Scaling only helps if you score well. A raw 60 in Extension 2 will not produce a better scaled mark than a raw 85 in Maths Advanced. Choose subjects where you can genuinely perform.
Is English scaled down for everyone?
Yes, but it is compulsory. You must include at least 2 units of English in your ATAR aggregate. The scale-down is modest and unavoidable, so focus on maximising your English mark rather than worrying about the scaling.
When does scaling happen?
UAC releases scaled marks in mid-December, after all HSC exams are marked and NESA has published results. You see your raw marks, aligned marks, and scaled marks in the same results report.
Want to model your ATAR before results day?
Use our free ATAR calculator to see how your predicted marks scale across subjects.
Try the ATAR Calculator →