HSC ATAR calculator (NSW and ACT): estimate your ATAR from HSC marks with UAC's 2025 scaling report, how each course scales (Table A3), the ten-unit aggregate with two units of English, the 2025 aggregate each ATAR needed (Table A9), why an ATAR is lower than the marks, and a printable

An HSC ATAR calculator is really three tables: UAC's Table A3, which shows for every course the HSC mark and the scaled mark at five percentiles; the ten-unit aggregate rule; and Table A9, the lowest aggregate for each ATAR. This page has all three from UAC's Report on the Scaling of the 2025 NSW HSC, a calculator that uses them, and the warning UAC itself prints about the first table, so you know exactly what kind of estimate you are reading.

Download the HSC scaling and ATAR table (PDF) (the 2025 HSC mark and scaled mark at the 50th, 75th and 90th percentiles of every main course, the ten-unit rule with a worked example, the lowest aggregate for each ATAR in 2025, and a planner; two pages, free).

The calculator

How the HSC ATAR is built

Two marks per course. NESA reports an HSC mark (out of 100 for a 2-unit course), which is the average of the moderated school assessment mark and the examination mark after both are aligned to the performance bands. UAC never uses it. UAC takes the raw examination and moderated assessment marks, which sit lower and are spread wider, and scales those. Table A3 shows both for every course so that students can see the relationship, and UAC warns in the table's notes that it "should not be used as a simple HSC to scaled mark conversion table".

Scaling. Each course's raw marks are adjusted so that the scaled marks of its students reflect how those students did in all their courses. A course taken by strong students scales high: the median scaled mark in Mathematics Extension 2 in 2025 was 44.7 out of 50 per unit, in Chemistry 33.9, in English Advanced 33.7; a course taken by a wider range scales lower: Mathematics Standard 2 23.2, Community and Family Studies 17.8, Mathematics Standard 1 12.5. The top of every course reaches 50.

The aggregate. The best 10 units of scaled marks, including at least 2 units of English, out of 500. A 2-unit course contributes two units at its per-unit scaled mark; English Extension 1 and 2, the other Extension courses and Studies of Religion I are 1 unit. Students with more than 10 units have the surplus dropped; a student with exactly 10 has every unit counted, including the weak ones.

The ATAR. Table A9 lists the lowest aggregate for each ATAR in each of the last five years. The median ATAR in 2025 was 70.75, and 17.3 percent of ATAR students were at 90 or above.

2025: HSC mark and scaled mark at the 50th, 75th and 90th percentiles

Per unit, out of 50 (double both for a 2-unit course's HSC mark out of 100). Read a row as: a student at the median of this course had this HSC mark and this scaled mark.

All 85 courses with percentile data are in the calculator, and the whole of Table A3 with means and maxima is read in HSC scaling explained.

The lowest aggregate for each ATAR, 2025 (UAC Table A9)

The same ATARs in 2021 to 2024 needed aggregates within about five points of these, so a target aggregate is a fair plan; it is not a promise.

What moves an HSC ATAR most

1. The weakest counted course. With exactly 10 units every unit counts; with 11 or 12 the aggregate drops the worst, so a weak sixth course is harmless and a weak fifth is not.
2. The English units, whatever they score. Two units of English are in the aggregate by rule. In 2025 the median scaled mark in English Standard was 20.0 per unit and in English Advanced 33.7, which is why the choice between them, and the work put into either, moves the aggregate more than almost any other decision.
3. Position, not mark. UAC's own examples show two students with the same average HSC mark and ATARs ten points apart, because one was near the top of easier courses and the other in the middle of harder ones. The calculator shows the course percentile for each mark for this reason.
4. Extension courses count one unit at a high scaled mark. Mathematics Extension 1 had a median scaled mark of 41.5 out of 50 in 2025; as the tenth unit it beats the second unit of nearly anything.

Download the HSC scaling and ATAR table (PDF) (the 2025 HSC mark and scaled mark at the 50th, 75th and 90th percentiles of every main course, the ten-unit rule with a worked example, the lowest aggregate for each ATAR in 2025, and a planner; two pages, free).

Where to get help

A 1-on-1 online class with a tutor who holds a master's in mathematics and teaches Year 11 and 12 maths, physics and chemistry to Australian students at Australian times (7:30 am before school, 4 pm to 6:30 pm after school, and weekend mornings, Sydney time): the estimate above read together in the free 30-minute first class, the subject where five marks buys the most ATAR found, and the term spent on it with every line of working read. The Year 12 Australia page says what the class works on in each state's course.

Questions parents ask

See how we teach this, 1-on-1 online →