How is the ATAR calculated in Western Australia?
In WA the ATAR is calculated by TISC from a student's best four scaled scores, not their raw school marks. Each ATAR course is scaled against the whole state cohort, the best four are added into a Tertiary Entrance Aggregate, and that aggregate is converted into a rank between 0 and 99.95. Everest Tutoring teaches eight of those courses.
Written by Aaron, Tutor. Updated 13 September 2026
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The three steps that turn marks into a rank
Step one: each ATAR course produces a combined score from school assessment and the WACE examination, moderated so that schools are comparable.
Step two: TISC scales each course against the performance of everyone who sat it. Scaling is not a bonus or a penalty; it is how a mark in one course is made comparable with a mark in another.
Step three: the four highest scaled scores are added to form the Tertiary Entrance Aggregate, and that aggregate is ranked against the whole Year 12 cohort to produce the ATAR. Because only four count, a fifth course acts as insurance rather than addition.
This is why the fastest way to lift an ATAR is usually the weakest of the four counting courses, not the strongest. Ten marks recovered in a low course moves the aggregate more than three in a high one.
How scaling tends to behave by subject group
TISC publishes the actual scaling for every course every year, and the numbers move. What is stable is the direction, because scaling follows the strength of the cohort that chooses each course. Use the table as a guide to course selection, then check the current year on the TISC site before deciding.
| Subject group | Courses | How scaling usually behaves |
|---|---|---|
| Higher mathematics | Mathematics Methods, Mathematics Specialist | Scales up strongly; the cohort is small and academically strong |
| Physical sciences | Chemistry, Physics | Scales up; consistently among the stronger cohorts |
| Life sciences | Human Biology, Biology | Around the middle; large and mixed cohorts |
| Applied mathematics | Mathematics Applications | Around or slightly below the middle |
| Humanities and social sciences | Economics, Politics and Law, Modern History | Varies by course; Economics has historically been one of the stronger of this group |
| English courses | English, Literature | Around the middle; required for competency, so effectively unavoidable |
What this means in practice
Choose four courses you can score well in, and take a fifth as protection. A course you enjoy and can hold at a high mark generally beats a hard-scaling course you cannot.
Then treat the weakest of the four as the project for the year. Everest Tutoring runs weekly one-hour classes capped at 10 in Mathematics Methods, Specialist, Applications, Chemistry, Physics, Human Biology, English and Economics at $400 per 10-week term, with a marked practice exam before each school assessment block.
Sources: Tertiary Institutions Service Centre · School Curriculum and Standards Authority
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