11 May 2026 · 7 min read
Most South Australian students do not fully understand how their SACE results convert into an ATAR — until after the fact. Here is exactly how the calculation works, what subject scaling does, and how to use this knowledge to choose subjects strategically.
The Australian Tertiary Admission Rank (ATAR) is not a score out of 100. It is a percentile rank that indicates where a student sits relative to their entire age cohort — including students who did not finish Year 12. An ATAR of 90 means the student performed better than 90% of their age group, not that they scored 90% in their subjects. In South Australia, the ATAR is calculated by SATAC (the South Australian Tertiary Admissions Centre) based on a student's results across their best SACE Stage 2 subjects. Understanding this distinction matters because it changes how you should think about subject difficulty and competition.
SACE Stage 2 subjects are graded A+ through E-. These grades are converted to a numerical score on a scale of 0 to 20, called a subject score. An A+ converts to 20, an A to 19.5, an A- to 19, a B+ to 18, and so on. These subject scores are then aggregated across your best subjects to produce a total score, which is then converted to the ATAR using a statistical table that compares South Australian student performance against a national standard. The conversion is not linear — the difference in ATAR between a 98 and a 99 is much harder to achieve than the difference between a 70 and a 71.
Not all SACE subjects contribute equally to the ATAR — this is the effect of scaling. Scaling adjusts raw subject scores to account for the difficulty of the cohort sitting the subject. A subject taken by a high-achieving cohort is scaled up; a subject taken by a lower-achieving cohort is scaled down. In practice, subjects like Mathematical Methods, Physics, and Chemistry tend to scale up. Subjects with larger or more diverse cohorts tend to scale more neutrally. The scaling factors change every year depending on who takes each subject, so it is impossible to say with certainty that Subject X will always scale well. What is certain: choosing a difficult subject and performing well is almost always better than choosing an easy subject because you expect a higher grade.
Your ATAR in South Australia is calculated from your best 90 credits of Stage 2 SACE subjects, plus a compulsory Research Project. Most Stage 2 subjects are worth 20 credits, so you typically need results from at least four Stage 2 subjects for the ATAR calculation, with additional subjects contributing if they improve your score. The Research Project is worth 10 credits and is compulsory — it contributes to the ATAR but cannot be replaced by other subjects. Students who perform poorly in the Research Project cannot exclude it from their ATAR calculation.
Three misconceptions consistently cause South Australian students to make poor strategic decisions:
The strategic implication of how ATAR is calculated is that subject choice matters more than most students appreciate. Choosing subjects where you are genuinely capable of achieving an A or A+ will almost always produce a better ATAR than choosing subjects you find easy but where your ceiling performance is a B+. The best subject choices are the intersection of three factors: subjects that scale reasonably, subjects where you can realistically achieve top grades, and subjects that satisfy prerequisites for your target university courses. If those three don't fully overlap, prerequisites should be treated as non-negotiable constraints, and you optimise the remaining choices.
Want help applying these strategies to your own study? Book a free consultation with the Titanium Tutoring team.