How the HSC ATAR Works (NESA, UAC): Scaling, Aggregate and Subjects

Your HSC ATAR is a rank from 0.00 to 99.95 that UAC (not NESA) calculates from your scaled marks in 10 units of ATAR courses: your best 2 units of English plus your best 8 units from everything else. Scaling adjusts each course for the strength of the students taking it, so a course's scaled mean says more about its cohort than about how hard it is. UAC's advice is to choose courses for your interests and ability, not for scaling. To see the 2025 scaled figures for every course and estimate your own ATAR, use the HSC ATAR calculator.

This guide describes UAC's ATAR Essentials 2026, written for students completing the HSC in 2026, and the figures in UAC's Report on the Scaling of the 2025 NSW HSC. Scaling is redone every year, so your own scaled marks will differ from the 2025 ones, and since 2025 there is no Category A or B course rule. For what the HSC is, see how the HSC works. For results day, see HSC results. For the performance bands, see HSC bands. The HSC hub links every subject.

What is the HSC ATAR and how does it relate to the HSC?

The Australian Tertiary Admission Rank (ATAR) is a number from 0.00 to 99.95 in steps of 0.05. It ranks you against your age cohort, so an ATAR of 80.00 places you in the top 20%. UAC says there is no pass or fail, and that universities use it to rank applicants for courses that select on it.

The HSC and the ATAR are two separate results with two separate owners. NESA aligns your marks to performance bands and produces your HSC marks. UAC does the scaling and calculates the ATAR. UAC's own table sets them side by side:

Because most students score between 70 and 80 (Band 4), that group spreads out when ranked. UAC says marks around 70 could lead to an ATAR in the 50s, and marks closer to 80 to an ATAR around 80.00, depending on what you study. UAC says most courses have a median mark above 75, while the median ATAR is usually around 70. Its 2025 report gives a median ATAR of 70.75 across 60,432 ATAR recipients.

The top of the scale is 99.95. UAC's 2025 report says 53 students received it. For the date and how to see your ATAR, see HSC results. To understand bands and why a Band 6 is not a high ATAR, see HSC bands.

Who can get an HSC ATAR?

To be eligible, you must have satisfactorily completed at least 10 units of ATAR courses in Year 12, and those courses must include at least:

• 2 units of English
• three courses of 2 units or more
• four subject areas.

Read these as conditions on the same 10 units, not as extra units on top. The fourth is the one that catches people. Within a subject area there can be several courses: the Mathematics courses from Standard 1 to Extension 2 are one area, and UAC's own wording treats them that way. Our calculator, which follows UAC's eligibility rules, flags a set of courses that fails any of the four.

An ATAR course has to be a NESA Board Developed course with an HSC exam. UAC adds that VET courses count only if you sit the optional exam. A student on the International Baccalaureate or a tertiary preparation program does not get an ATAR and is given a UAC rank if they apply through UAC. NESA's own rules for the HSC itself are in how the HSC works.

How is the HSC ATAR calculated?

Your ATAR is based on the sum of your scaled marks in 10 units: your best 2 units of English, then your best 8 units from the remaining courses. UAC works through it in six steps:

1. Raw HSC mark. For each course, UAC averages your raw exam mark and your moderated school assessment mark. These raw marks are not reported to you.
2. Percentile. UAC finds where you sit in each course against the other students in it.
3. Scaling. It converts each raw mark to a scaled mark, so courses can be compared (see the next section).
4. Aggregate. It adds the scaled marks from your best 2 units of English and your best 8 units from the rest.
5. Overall percentile. It places your aggregate against everyone of HSC age in NSW.
6. ATAR. It truncates that percentile to the nearest 0.05.

Two points follow from this. First, it is the raw marks that get scaled, not the aligned HSC marks on your results page, so you cannot take your HSC marks and check the calculation yourself. Second, English is a reserved slot: your best 2 units of English are always in the 10, even when another course would have given a higher aggregate.

If you study more than 10 units, UAC drops the lowest scaled units. It can drop just one unit of a 2-unit course: in UAC's sample ATAR notice, 1 unit of Mathematics Advanced is included and the other omitted. After results you can see which of your courses, and how many units of each, were included.

To run a set of courses and marks yourself, use the HSC ATAR calculator. It takes your courses and HSC marks, applies UAC's 2025 scaling and shows an estimated ATAR. Treat it as an estimate. Your real ATAR depends on this year's scaling and the whole cohort.

How does HSC scaling work?

UAC describes scaling as working out what your marks would have been if all students attempted all courses and all courses were marked to produce the same distribution of marks. It does that by changing each course's mean, standard deviation and maximum mark.

The scaled mean of a course is based on how the students in that course performed in all their courses. If the students in a course tended to do well in their other courses too, the course has a high scaled mean. If they range from high to low, it has a low one. UAC says a low scaled mean does not stop you getting a high ATAR in that course.

HSC marks and scaled marks answer different questions. An HSC mark says you reached a standard. A scaled mark says where you would have placed if the whole cohort had done the course. UAC says scaled marks are generally lower than HSC marks, which is expected, and that comparing the two does not tell you much.

A few rules sit on top of this:

• English is scaled as one group. NESA puts English Studies, English Standard and English Advanced on a common scale, so UAC scales them as a single group.
• Most extension courses take their scaled mean and spread from the extension students' performance in the matching 2-unit course.
• Scaling is done afresh every year, in the year you complete the course. If you accumulate your HSC, your marks are not rescaled in the year you become eligible for an ATAR.
• The school you attend and your postcode do not matter. Nor does the share of students in Band 6 in a course.

HSC scaling subjects: what do scaled means show?

Students often search for "highest scaling subjects". UAC publishes scaled figures for every course with enough students, in Table A3 of the scaling report. The table below is a selection of 15 courses from the 2025 report, grouped by area (not ranked). Marks are per unit, out of 50, so a 2-unit course reports twice these figures out of 100.

Source: UAC, Report on the Scaling of the 2025 NSW HSC, Table A3 (UAC reference licence); unit values from UAC's list of 2025 HSC courses. Figures describe the 2025 cohort only. UAC covers every course with enough students, and the calculator lists them all.

Read the table with UAC's own caution. A course's scaled mean reflects the students who took it: where the candidature is made up of students who did well across all their courses, the scaled mean is high. UAC names Mathematics Extension 2 and Physics as examples of courses that usually have high scaled means because high-achieving students take them. UAC's 2025 report also says the most able students generally choose the more demanding courses where they have a choice. A high figure here is therefore a description of who took the course, and it is not a bonus you receive for enrolling.

Visual Arts shows the other side. Its students' mean HSC mark is 40.9, higher than Business Studies, but its scaled mean is lower than Business Studies. Your own position in the course matters just as much as the course's scaled mean, and UAC says so. A student at the top of a course with a low scaled mean can still finish high, and every course in the 2025 report has students with high ATARs.

To see the scaled mark for any HSC mark in any course, use the scaling lookup in the HSC ATAR calculator. It estimates the scaled mark from the course's 2025 scaled distribution, for every course UAC reports.

What aggregate gives which ATAR?

Once every aggregate is calculated, UAC ranks them and converts the position to an ATAR. The table shows the lowest aggregate that gave each of a set of ATARs in 2025, from UAC's report.

Source: UAC, Report on the Scaling of the 2025 NSW HSC, Table A9, 2025 column (UAC reference licence). The aggregate needed changes each year with the cohort.

If your aggregate falls between two rows, your ATAR sits between them, and the HSC ATAR calculator estimates that step for you. To compare an ATAR with university courses, the HSC course ATAR list shows what NSW and ACT courses accepted last year. UAC adds that a published lowest selection rank can include adjustment factors that the lowest ATAR does not, so a lowest ATAR is not necessarily the ATAR needed for an offer.

How should I choose HSC subjects?

Start with the fixed rules, then with what you want to study next.

1. Choose from interest and ability. UAC's report says choice should be determined only by your interests, your demonstrated abilities and the value of courses for your career plans, and that scaling is designed so that students are not disadvantaged by their choice.
2. Count the units. You need 10 units of ATAR courses, including 2 units of English, three courses of 2 units or more and four subject areas. Most courses in UAC's list are 2 units, and many extension courses are 1 unit. Studying more than 10 units does not guarantee a higher ATAR. UAC's data show that students with more units tend to get higher ATARs, but it cautions that you cannot assume extra units cause that, and only 10 units count.
3. Plan for English. English always counts, so choose the English course that fits you and give it the time. English Studies, Standard and Advanced are scaled as one group. UAC's tables list English Studies and Mathematics Standard 1 as exam courses.
4. Watch the subject areas. Several maths courses count as one area, so a program of three maths courses and English is still short of four areas. English Advanced and its extensions are one area too.
5. Check how extension courses attach. An extension course counts only if you satisfactorily complete the matching 2-unit course. The exception is mathematics: you can complete Extension 1 and Extension 2 without Mathematics Advanced, though Extension 2 needs Extension 1. If you complete both, UAC considers them separately, and one, both or neither can count.
6. Know that some courses are alternatives. You sit one English course, not two, and Beginners and Continuers in the same language are alternatives too. Our calculator counts only the higher result from each such set. Confirm which combinations your school allows.
7. Check university prerequisites first. UAC's example is a Bachelor of Advanced Computing that lists Mathematics Advanced (Band 4): without that band you are not considered, whatever your ATAR. Prerequisites are set by each university and course, so read the entry requirements for the degrees you might want.
8. Know that performance can raise your selection rank. Some universities lift an applicant's selection rank for strong results in a specific course or for the Educational Access Scheme. UAC says that raises your selection rank for that course and leaves your ATAR unchanged.

You do not need a particular maths course for the ATAR itself. In 2025, 13.4 per cent of ATAR-eligible students did not complete a maths course. A prerequisite for the degree you want is a different matter.

For what each course covers, see the HSC syllabus guide. The subject pages are the place to practise with past papers, for example HSC Biology, HSC Chemistry and HSC Mathematics Advanced.

Common mistakes about the HSC ATAR and scaling