All About ATAR & Scaling Part 1 [Free eBook]

Posted on December 24, 2013 by Matrix Education


To maximise your HSC results, it’s important to know how your ATAR is calculated and how scaling impacts your results. In this post, we explain all about ATAR & Scaling.

1. What is an ATAR?

The Australian Tertiary Admission Index (ATAR) is a number between 0.00 and 99.95 with increments of 0.05. It is a numerical measure of a student’s overall academic achievement in relation to other HSC students.


Remember, ATAR is a rank and not a mark.
Have a look at Jack’s results to understand the difference between his HSC marks and ATAR.
Jack obtained an ATAR of 99.7
It means Jack performed better than 99.7% of his cohort.
See his results below.

blog_ATAR_Certificate blog_hsc_results

Above are copies of an actual student’s HSC and ATAR certificates.

1a. Why do we need the ATAR?

The ATAR allows universities to rank students for selection into their courses. It’s calculated by universities and released by the UAC. Visit UAC website to view cut-offs for different university courses or visit the Matrix ATAR Calculator to search the University Courses.

1b. Why don’t universities use HSC marks for selection into their courses?

Students study different combinations of HSC subjects. Therefore comparing a student’s overall performance based on HSC marks is difficult.
For example, how would you compare Jack’s result of 95 English Advanced with his friend who scored 97 in English Standard? Who performed better ? In order to compare a student’s overall performance fairly and equitably, UAC converts this into a UAC score and then into your ATAR.

1c. What is ATAR used for?

Universities use your ATAR on its own or with other selection criteria, to rank and select applicants for admission into university courses.

1d. Who is eligible for an ATAR?

To be eligible for an ATAR you must satisfactorily complete at least 10 units of ATAR courses.
These ATAR courses must include at least:

  • eight units from Category A courses (courses that have academic rigour and depth of knowledge providing an adequate background for tertiary studies.)
  • two units of English
  • three ATAR courses of two units or greater
  • four subjects.

1e. How is the ATAR calculated?

A student’s ATAR is a rank which is based on an aggregate of scaled marks in 10 units of ATAR courses comprising of:

  • their best two units of English
  • their best eight units from their remaining units, which can include up to two units of Category B courses.

The flowchart below outlines the process of determining your ATAR.

ATAR calculation flow chart

2. What are HSC Marks?

HSC marks provide information about how well you have performed in each of the courses you have completed. Please see the table below for further details.


Note that the HSC Mark is the average of HSC Exam mark and moderated assessment mark.

Read: How does the moderation of HSC assessment marks work?


Below are the HSC results that are released a day before ATAR results. The Board of Studies issues students with HSC Record of Achievement (view sample below) which provides a profile of your performance in the different courses you have studied. It includes information regarding your exam mark, assessment mark, HSC mark and performance band.


3. What is scaling? 

Scaling of HSC marks is the process of ‘standardising’ raw marks (HSC Marks = average of HSC exam mark and assessment mark) provided by the BOS and estimating what these marks would have been if all courses had been studied by all students.

At the end of this scaling process, different marks in different subjects are converted to a single UAC score for every subject. Although scaled marks generally differ from the raw marks from which they are derived, the ranking of students within a course is not changed.

You can compare scaling to a conversion of foreign currency (HSC Mark of a subject) to the Australian currency (scaled mark of a subject).
As different exchange rates apply to different currencies, so are different conversion rates applied to HSC marks of different subjects when they are converted to scaled marks for comparison.

3a. Why is scaling necessary?

How do you compare one student who scored a 90 in Mathematics Ext 2 to another student who scored 90 in Mathematics Advanced? The answer is impossible without scaling!

For example, the table below shows HSC marks in Maths Ext 2 and Maths ADV can only be compared fairly using scaled marks.Since each student undertakes a different combination of subjects, their performance in one subject will not necessarily reflect their ability in different subjects. Same marks in different courses are not necessarily equal, just as different currencies are compared using the exchange rate, scaling is used to compare marks from different courses. It allows a comparison of marks from ‘difficult’ and ‘easy’ subjects. The underlying principle of scaling is that a student should neither be advantaged nor disadvantaged by choosing one HSC course over another.

Scaling HSC

4. Do my HSC Subjects scale well?

4a. English courses

The ATAR is based on an aggregate of scaled marks in 10 units of ATAR courses in which your best two units of English are taken into account. Therefore English plays an important role in determining whether you get a good ATAR or an exceptional ATAR.

If you are good at English, consider Advanced or Extension English. If you are capable of undertaking Advanced English as one of your ATAR courses, then you should avoid undertaking Standard English as it is not a subject that is scaled well.

A mark in the top 30% [P70 or 70th percentile] in Advanced English is equivalent to a scaled mark (37/50) in the top 1% [P99 or 99th percentile] in Standard English.

Use the Matrix ATAR Calculator to convert your HSC mark into Percentile and Scaled marks.

4b. Mathematics courses

If you are good at Mathematics, consider Maths Ext 1 or Ext 2. If you choose General Maths, you must ace it.

If you are a capable Mathematics student and are deciding between Extension 1 & Extension 2 Mathematics, you should still undertake Extension 2 Mathematics. Mathematics Extension 1 & 2 is scaled very well. You only need to be in the top 16% [84th Percentile] and the top 36% (64th Percentile) of Mathematics Ext 1 and Ext 2 respectively to achieve a mark equivalent to the top 2% (98th Percentile) in Mathematics.

4c. Science courses

Chemistry and Physics scales slightly better than Biology. If you are aspiring to study Medicine, you should consider Biology as one of your HSC subjects.

From the scaling graphs, we can see that at the 90th Percentile, you will receive the following scaled marks:

  • Chemistry: 41/50 (82/100)
  • Physics: 40/50 (80/100)
  • Biology: 39/50 (78/100)

The difference in scaled marks is less at the higher percentiles such as at the 99th Percentile.

4d. Humanities courses

Economics scales better than business studies or legal studies.

Modern History scales better than Ancient History. Extension subjects such as History Extension always scales well.

If you do are at good at Music, consider Music 2 or Music Extension over Music 1.

4e. Language courses

If you are good at languages, consider Continuers over Beginners. Refer to the scaling graphs of Japanese Continuers and Japanese Beginners.
Latin continuers and Latin Extension are the best scaling courses for Languages.

5. Choosing the right subjects

Students are advised to consider the following questions when selecting subjects for Year 11 & 12.

  1. Do I find the subject interesting and/or do I like the subject? For example, do I find science subjects more interesting than humanities subjects?
  2. Do I understand clearly what the subject involves? For example, junior science is very different to Chemistry, Physics and Biology.
  3. Is the subject a prerequisite for the university course that I hope to undertake? For example, if I want to undertake a Medical course at University, then should I consider studying both Chemistry and Biology?
  4. Do I understand the scaling of the subject? Subject selection should not depend on the scaling of each subject alone. No matter how well a subject is scaled, if you do not perform well in the subject then scaling does not help.

Want to achieve an ATAR of 99.95? 

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