ATAR guide · Sydney
HSC scaling explained without the myths.
Scaling compares achievement across courses. It does not permanently label a subject “good” or “bad”, and it should not be the only reason to choose one.
Key points
What scaling is trying to solve
Students take different combinations of HSC courses, so raw marks cannot simply be added as if every course had the same candidature and pattern of achievement. UAC’s scaling process creates a basis for comparison when forming ATAR aggregates.
Scaling reflects how the course candidature performs across their other courses. It is recalculated for each cohort, which is why simplified scaling tables and subject rumours can be misleading. Strong performance remains more useful than choosing a supposedly high-scaling course that does not suit the student.
Essential ideas
What to understand before making a decision.
Raw marks are not directly added
HSC marks are not simply totalled to produce an ATAR.
Scaling varies by year
Patterns can change because the candidature and results change.
Position within a course matters
A strong result can contribute well even when a course is casually described as low scaling.
Suitability still matters
Interest, prerequisites and the likelihood of high achievement belong in subject choice.
How it works
How HSC scaling works.
- 01
Compare
Scaling puts different course results onto a comparable basis.
- 02
Aggregate
Scaled marks contribute to the best ten eligible units.
- 03
Rank
The aggregate helps determine the student’s ATAR position.
- 04
Choose
Subject decisions should balance aptitude, goals and prerequisites.
Common questions
Common ATAR questions.
Does a difficult subject always scale up?
Not automatically. Scaling is based on candidature performance patterns, not a fixed judgement about course difficulty.
Should I drop a subject because it scales poorly?
Scaling alone is not enough reason. Consider performance, interest, university prerequisites, workload and advice from the school.
Are online scaling calculators exact?
No. Future scaling cannot be known exactly, and public calculators generally use historical or modelled relationships.