Understanding HSC scaling can feel overwhelming as you approach your final year of high school. At KIS Academics, we’re here to help you maximise your results by breaking down exactly how scaling works and how your ATAR is calculated — so you can focus on what matters most: studying smart and doing your best!
If you’re still unsure about how the ATAR is calculated overall, check out our detailed guide on the ATAR for a full picture.
Manoj Arachige
How Are Your Final HSC Marks Calculated?
Your final HSC mark for each subject is a combination of two parts:
- 50% from your HSC exam
- 50% from your moderated internal assessments (like assignments, tests, and trials)
Both your exam marks and internal assessment marks undergo moderation and scaling. Let’s unpack what this means.
Internal Assessment Marks: What Happens Behind the Scenes?
Throughout Year 12, each subject has at least three assessments, which are weighted and averaged to give you a raw internal mark. But here’s where many get confused — your raw internal mark is not the same as the final internal mark used for your HSC calculation!
Why? Because raw internal marks are moderated relative to your school’s overall performance compared to the entire state.
Example:
- School 1 has an average internal assessment mark of 80 in Maths Advanced
- School 2 has an average internal assessment mark of 60 in Maths Advanced
- Both schools have an average HSC exam mark of 70
It wouldn’t be fair to simply average these internal marks with the exam marks because students from both schools performed similarly in the final exam. So NESA uses a statistical algorithm to scale internal marks to match the performance trends of each school’s cohort in the final exam.
- School 1’s internal marks may be scaled down (from 80 to a lower mark)
- School 2’s internal marks may be scaled up (from 60 to a higher mark)
This adjustment accounts for differences like assessment difficulty, marking standards, and student ability between schools.
Manoj Arachige
How Does This Affect Individual Students?
The moderation process aligns the school’s average internal mark with its average HSC exam mark, then adjusts the top and bottom internal marks to match the highest and lowest exam marks in that school cohort.
For example:
- Student A ranked 1st in internal assessments but scored 90 in the final exam
- Student B ranked 2nd but scored 96 in the final exam
After moderation, Student A’s internal assessment mark would be adjusted to 96 (reflecting their top rank in internals), and Student B’s internal mark would be adjusted to 90.
Your final HSC mark for the subject would be the average of:
- Your moderated internal mark
- Your actual HSC exam mark
So for Student A:
(96+90)/2=93(96 + 90) / 2 = 93(96+90)/2=93
Subject Scaling: Why Does It Matter?
Some subjects are considered to ‘scale well’ while others ‘scale poorly’ — but what does this actually mean? Subject scaling exists to reflect the relative difficulty of subjects and the overall capability of students in those subjects.
Take Standard English vs Advanced English:
- If the average exam score for Standard English is 80, and for Advanced English is 70, simply using these raw scores to calculate ATAR would be unfair.
- Advanced English is more difficult, and students tend to be more capable on average, so their marks are scaled up to reflect this.
- Standard English scores are scaled down comparatively.
This means raw marks in a subject are adjusted according to the cohort’s performance across all subjects, balancing out the difficulty and ability levels.
The takeaway? It’s a myth that ‘easier’ subjects are easier to get Band 6s in. More difficult subjects often have their marks scaled up, meaning more students can achieve Band 6s after scaling.
Should You Choose Subjects Based on Scaling?
It’s tempting to pick subjects just because they ‘scale well’, but this can backfire if you struggle with the content. Your final marks depend heavily on your performance and interest in the subject, and the performance of your school cohort.
Pro tip: Choose subjects you enjoy and are confident in — and consider past scaling reports to help inform your decisions.
For more resources and tips on navigating your HSC journey and maximising your marks, visit more of KIS Academics HSC study guides.
Manoj Arachige
How Does Your ATAR Get Calculated?
Once your final scaled marks are calculated, your best 10 units contribute to your ATAR — this must include 2 units of English.
- Each 2-unit subject contributes up to 100 points; 1-unit (extension) subjects contribute up to 50 points.
- Your total out of 500 is then ranked against all students in NSW who started Year 7 the same year as you.
- An ATAR of 80 means you scored better than or equal to 80% of those students.
Note: The ATAR calculation includes all students who started Year 7 that year — even those who dropped out or didn’t sit the HSC — which makes the average ATAR closer to 70, not 50.
Key Points to Remember:
- Your final HSC mark is your mark — it’s not adjusted by how well your school does, aside from the scaling processes described.
- Don’t stress too much about your raw internal marks — focus on ranking well against your peers.
- Encourage your schoolmates to do their best too! Higher cohort performance benefits everyone’s internal assessment moderation.
- Choose subjects you enjoy, not just ones that ‘scale well’. Performance and interest lead to better results.
- Beware of ATAR calculators that don’t account for school scaling or cohort rankings — they can give inaccurate predictions.
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📚 Frequently Asked Questions
1. Are raw year 12 internal marks important
Not directly. Raw internals are adjusted based on your school’s HSC exam performance. Focus on ranking as high as possible in assessments.
2. What is the purpose of scaling in the HSC
Scaling balances differences in difficulty and student ability across subjects to ensure fair ATAR calculations.
3. How are the best 10 units chosen for ATAR?
Your top 10 units (including 2 English units) are combined and ranked statewide to calculate your ATAR percentile.
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