Is Taking Twelve Units in Year 12 Better Than Taking Ten?

A 12-unit HSC load can give you a safety net, but it does not automatically produce a higher ATAR. In NSW, UAC calculates your ATAR using 10 units: your best 2 units of English, plus your best 8 units from your remaining eligible courses. If you take 12 units, the extra two can help by replacing lower-performing units in the calculation. They do not earn bonus points simply for being there.

The real decision is whether those extra two units give you enough protection to justify the additional workload. For some students, 12 units is a sensible backup. For others, taking 10 units and putting more time into their strongest subjects is the better strategy.

## What are the actual rules?

There are three separate things to understand: NESA's requirements for receiving an HSC, UAC's requirements for receiving an ATAR, and your school's own subject-selection policies. They overlap, but they are not interchangeable.

### NESA: You need at least 10 units for the HSC

Under the current NSW Education Standards Authority (NESA) rules, students must satisfactorily complete:

- At least 12 units of Preliminary courses.
- At least 10 units of HSC courses.

Your HSC pattern of study must also include:

- 2 units of a Board Developed English course.
- At least 4 additional units of Board Developed courses.
- At least three courses worth 2 units or more.
- At least four different subjects.

The three courses worth 2 units or more can be Board Developed or Board Endorsed courses.

This means that **10 units is the statewide minimum for your HSC, not a requirement to study 12 units in Year 12**.

You can read the current requirements in [NESA's Pattern of Study rules](https://curriculum.nsw.edu.au/ace-rules/ace12/nesa-pattern).

### UAC: Getting an ATAR has additional requirements

Having 10 HSC units does not automatically make you eligible for an ATAR.

For a standard NSW ATAR, UAC requires you to satisfactorily complete at least:

- 10 units of Board Developed courses.
- 2 units of English.
- Three Board Developed courses worth 2 units or more.
- Four different subject areas.

Notice the difference. NESA allows some of the courses contributing to your HSC pattern to be Board Endorsed. UAC's standard ATAR eligibility rules require all 10 units to come from Board Developed courses.

Your ATAR is then calculated using:

| Component | Units included |
|---|---:|
| Best English units | 2 |
| Best remaining eligible units | 8 |
| **Total** | **10** |

If you study 12 eligible units, UAC does not add all 12 to your aggregate. It selects the best 10 according to the applicable scaling and unit rules.

There is another important detail: you must still satisfy the four-subject-area requirement to receive an ATAR, even though the units contributing to your final aggregate can come from fewer than four subject areas.

You can check the current requirements in [UAC's ATAR eligibility FAQs](https://uac.edu.au/future-applicants/faqs-and-forms/atar) and its guide to [how your ATAR is calculated](https://uac.edu.au/future-applicants/atar/how-your-atar-is-calculated).

01What does taking 12 units actually buy you?

Think of the extra two units as insurance.

Suppose you study six standard 2-unit courses, giving you 12 units altogether. Two units come from English, leaving 10 units across your other five courses.

UAC takes your best 8 of those remaining 10 units. If all five courses are worth 2 units, the lowest-performing course, measured by its scaled mark, can be left out of the ATAR aggregate.

That gives you some protection. One weaker subject does not necessarily damage your ATAR.

There are two important conditions, though.

First, the extra course must be eligible to contribute to your ATAR. A course that contributes to your HSC but is not an eligible ATAR course does not provide the same backup.

Second, UAC uses scaled marks rather than simply dropping whichever subject has your lowest HSC mark. This makes a difference when comparing subjects.

Scaling does not give you a guaranteed bonus

You might hear that Mathematics Extension 2 or Physics scales well, and conclude that taking one of these subjects will automatically improve your ATAR.

That is not how scaling works.

UAC adjusts marks to make results from different courses comparable. The process considers the academic performance of the students taking each course across their HSC subjects. Courses with strong overall-performing cohorts tend to produce higher scaled marks at the top end.

However, you still need to perform well in the course. Choosing a subject because it scaled strongly in a previous year does not guarantee that it will improve your aggregate.

Scaling statistics also change from year to year. UAC’s ATAR Compass uses historical scaling data to estimate results, not to promise an exact ATAR.

There is another detail worth knowing: scaled marks are not reported to students. You cannot reliably identify the units UAC will exclude simply by looking at your HSC marks.

For this reason, choose subjects based on your ability, interests, and future study plans rather than trying to predict which course will give you the biggest scaling advantage.

Extension courses can change the calculation

If you study Mathematics Extension 1 or Extension 2, be particularly careful when counting your units.

UAC has specific rules for extension courses. For example:

• Mathematics Extension 1 contributes 1 unit when studied with Mathematics Advanced.
• When studied with Mathematics Extension 2, Mathematics Extension 1 contributes 2 units to the ATAR calculation.
• If you complete Mathematics Advanced, Mathematics Extension 1, and Mathematics Extension 2, your Mathematics Advanced result is not included in the ATAR calculation.

English Extension courses also have their own unit arrangements.

The important point is that your ATAR is calculated using eligible units, not simply by selecting a certain number of subject names. Read UAC’s extension course rules before assuming that an extra subject will provide a full two-unit safety net.

02What is the cost of taking 12 units?

The advantage of 12 units is easy to see on paper. The disadvantage is less obvious until you consider what happens during the school week.

Every additional course brings more than another exam. It brings lessons, homework, assessment tasks, revision, and another set of concepts that you need to understand well enough to apply under exam conditions.

Your available time does not increase just because you have enrolled in another subject.

This creates an important trade-off.

Imagine you are studying 12 units. Your additional subject is going reasonably well, but preparing for its assessments takes time away from Mathematics Advanced, Physics, and Chemistry.

Those subjects might have contributed strongly to your ATAR if you had more time to consolidate difficult concepts and practise exam questions.

If your performance drops across several subjects, the extra course may not compensate for the lost marks. It is possible to finish 12 units with a lower ATAR aggregate than you could have achieved with a more manageable 10-unit load.

This is why the question is not simply whether you can handle another subject. It is whether you can handle another subject without compromising your performance elsewhere.

When is the extra workload worthwhile?

Taking 12 units can be a sensible choice if:

• You are performing consistently well across your existing subjects.
• You enjoy the additional subject and have a genuine interest in studying it.
• You can manage the assessment schedule without regularly sacrificing preparation in other courses.
• The extra course provides useful protection against a weaker result.
• It helps you maintain a broader selection of subjects while keeping your future options open.

Taking 10 units may be more sensible if:

• You are already struggling to keep up with your current workload.
• Your assessment results are suffering because you are spreading your attention too thinly.
• The additional subject is not particularly useful for your future plans.
• You would benefit from more time practising and consolidating your strongest subjects.
• Your wellbeing, sleep, or other commitments are being affected by the additional workload.

Neither option is automatically more ambitious or academically impressive.

A student taking 10 units who performs consistently well can achieve a stronger ATAR aggregate than a student taking 12 units whose results suffer under the extra workload.

Your school has a say, too

There is a difference between what NESA permits and what your school allows.

NESA’s minimum HSC pattern is 10 units, but this does not mean you can automatically decide to drop two units without consulting your school.

Schools have their own subject offerings, timetables, and approval processes. Your principal also has discretion when deciding whether to approve changes to HSC courses.

Under NESA’s current rules, students may request withdrawal from an HSC course before the HSC written examination. The principal must advise students of any consequences for their HSC eligibility and pattern of study requirements.

In other words, dropping a subject is a formal decision, not simply a matter of stopping attendance.

Before making the change, speak with your HSC coordinator and check that your remaining subjects still meet both NESA’s HSC requirements and UAC’s ATAR eligibility requirements.

If you’re still planning your senior subject load, our guide to How Many Units Should You Take in Year 11? explains how to approach the decision earlier in your HSC pathway.

If an additional subject creates a timetable clash, you should also consider What Should You Do If Two HSC Subjects Clash on the Timetable?.

03University prerequisites are a separate consideration

Your ATAR is not the only reason to choose a particular subject.

Some university degrees require you to have studied specific HSC courses and achieved a particular result. Others assume you have certain background knowledge, even if that knowledge is not formally required for admission.

These are two different things.

A prerequisite is a requirement you must meet to be eligible for admission to a particular university course.

Assumed knowledge is knowledge that the university expects you to have when you begin studying. You may still be admitted without it, but you could find the first-year content more difficult.

Neither should be confused with NESA’s statewide HSC requirements.

For example, the University of Sydney currently lists a Mathematics prerequisite for a number of its degrees, including Engineering courses. For NSW HSC applicants, the requirement is:

• Mathematics Advanced: Band 4, or
• Mathematics Extension 1 or 2: Band E3.

Mathematics Standard does not satisfy this particular prerequisite.

This is a University of Sydney admission requirement for the courses listed on its official Mathematics prerequisite page. It is not a statewide rule requiring every NSW HSC student to study Mathematics Advanced.

The rules can also differ between universities. UNSW, for example, states that it does not have formal subject prerequisites for its degrees, but some degrees and first-year courses have assumed knowledge. It recommends appropriate preparation or bridging courses if students do not have that knowledge. See UNSW’s assumed knowledge and bridging course guidance.

This matters when choosing between 10 and 12 units.

You might already have enough units for an ATAR, but your subject combination may not meet the admission requirements of your preferred degree. Adding an unrelated subject will not fix that problem.

Conversely, you might have all the subjects required for your preferred degree while taking only 10 units. There is no automatic university admission advantage to taking 12.

04Questions and solutions

Question 1

A student completes 12 eligible HSC units. These consist of 2 units of English and five other Board Developed courses worth 2 units each.

Assuming the student meets all ATAR eligibility requirements and satisfactorily completes every course, how many units contribute to the ATAR aggregate? How many non-English units can be excluded?

Solution 1

The ATAR aggregate includes 10 units: the best 2 units of English and the best 8 remaining units.

The five non-English courses contribute 10 units altogether. UAC selects the best 8, meaning 2 non-English units can be excluded.

Because all five courses are worth 2 units, this means one complete course can be left out of the aggregate.

The important distinction is that the excluded course is selected using scaled marks, not necessarily the lowest HSC mark.

Question 2

Taylor has completed a 10-unit HSC pattern consisting of:

• 2 units of English Advanced, a Board Developed course.
• 2 units of Physics, a Board Developed course.
• 2 units of Chemistry, a Board Developed course.
• 2 units of Mathematics Advanced, a Board Developed course.
• 2 units of a Board Endorsed course that is not eligible for ATAR calculation.

Assume Taylor satisfies NESA’s HSC pattern requirements and the four-subject-area requirement, and has satisfactorily completed every course.

Is Taylor eligible for a standard NSW ATAR? Explain the difference between the HSC and ATAR requirements.

Solution 2

Taylor is not eligible for a standard NSW ATAR because only 8 of the 10 units come from eligible Board Developed courses.

The student can satisfy NESA’s HSC pattern requirements with a combination of Board Developed and Board Endorsed courses, provided the minimum requirements are met.

However, UAC requires at least 10 units of Board Developed courses for ATAR eligibility.

The distinction is important: receiving an HSC and receiving an ATAR are not the same thing. A student can satisfy the HSC pattern but fail to meet the additional ATAR eligibility conditions.

Taylor would need to check their options with the school and ensure that the required 10 eligible Board Developed units and all other UAC conditions are satisfied.

Question 3

A student takes 12 units, including English and five 2-unit non-English courses.

Their HSC marks in the five non-English courses are:

The student assumes that Business Studies will be excluded because it has the lowest HSC mark.

Can they be certain that this course will be excluded from the ATAR calculation? Explain.

Solution 3

No. The student cannot determine which course will be excluded using HSC marks alone.

UAC uses scaled marks to calculate the ATAR aggregate. These marks account for the relative performance of students in different courses, so a higher HSC mark does not necessarily produce a higher scaled mark.

The tempting approach is to rank the five courses by their HSC marks and remove the lowest. However, that compares marks that have not been adjusted for differences between courses.

UAC’s scaling explanation includes examples where a course with a higher HSC mark produces a lower scaled mark than another course.

The student therefore cannot confidently identify the excluded course until the scaling process has been applied.

The broader lesson is that taking 12 units gives you a potential buffer, but you cannot assume that your lowest HSC mark will be the one removed.

Question 4

Two students meet all ATAR eligibility requirements and complete different study patterns.

Both have an English scaled mark of 65 and study standard 2-unit courses. All figures below are hypothetical scaled marks per unit.

Student A takes 10 units:

Student B takes 12 units:

Calculate each student’s aggregate. Does the student taking 12 units receive an advantage simply for completing an additional course?

Solution 4

Student A has the higher aggregate: 730 compared with Student B’s 722.

For Student A, all 10 units contribute:

\[ \begin{aligned} A &= 2(65+78+76+74+72)\\\ &= 130+156+152+148+144\\\ &= 730 \end{aligned} \]

For Student B, the lowest non-English course is excluded. The four highest non-English scaled marks are 77, 75, 73, and 71.

\[ \begin{aligned} B &= 2(65+77+75+73+71)\\\ &= 130+154+150+146+142\\\ &= 722 \end{aligned} \]

The difference is:

\[ 730-722=8 \]

Student B has completed more units, but the extra course does not compensate for the lower results across the units that contribute to the aggregate.

Notice that the additional course has not directly reduced the aggregate. It has simply failed to improve it enough to compensate for the weaker counted results.

If Student B’s additional course had produced a scaled mark of 80 instead of 68, while the other results remained unchanged, the four highest non-English marks would be 80, 77, 75, and 73. The aggregate would then be 740.

This demonstrates the actual benefit of 12 units: an additional strong result can replace a weaker one.

It also shows why 12 units is not automatically better. What matters is the performance that ultimately contributes to the best 10 units, not the number of units studied.

Question 5

Jordan completes 12 units, consisting of 2 English units and five other 2-unit Board Developed courses.

The courses cover exactly four different UAC subject areas. One of the five non-English courses is the only course Jordan has completed in the fourth subject area.

Assume that all courses are satisfactorily completed and that the lowest scaled mark belongs to this particular course. Its two units are therefore excluded from the ATAR aggregate.

Now consider a change: Jordan does not satisfactorily complete that course.

Assume the remaining 10 units still satisfy the HSC requirements, the 10-unit Board Developed requirement, the English requirement, and the requirement for three Board Developed courses of at least 2 units.

Is Jordan still eligible for an ATAR?

Solution 5

No. Jordan is no longer eligible for an ATAR because the remaining satisfactorily completed courses cover only three UAC subject areas.

This is different from simply having a low scaled mark.

Initially, Jordan has 12 satisfactorily completed units across four subject areas. The lowest-scoring course does not contribute to the aggregate, but it still contributes to satisfying the four-subject-area eligibility requirement.

Once Jordan fails to satisfactorily complete that course, it can no longer count towards ATAR eligibility.

The tempting argument is that the course was already excluded from the best-10 calculation, so losing it should make no difference.

That argument confuses two separate stages of the ATAR process:

1. Eligibility: Has the student satisfactorily completed the required courses, units, and subject areas?
2. Calculation: Once eligible, which scaled marks contribute to the 10-unit aggregate?

A course can be unnecessary for the aggregate but still necessary for eligibility.

This is why having 12 units is not an unconditional safety net. The additional courses can protect the aggregate against weaker results, but they do not remove the need to satisfy every eligibility requirement.

05So, is taking 12 units better than taking 10?

For most students, the decision comes down to how much value the extra subject provides compared with the time it consumes.

The strongest reason to take 12 units is that you want the additional subject and can manage it without sacrificing your performance elsewhere.

The strongest reason to take 10 units is that you would use the additional time more effectively by improving your understanding, assessment results, and exam preparation in your existing subjects.

Before deciding, work through three priorities:

1. Confirm that your remaining courses meet NESA’s HSC requirements and UAC’s ATAR eligibility conditions.
2. Check the actual prerequisites and assumed knowledge for the university courses you are considering.
3. Be realistic about whether the additional subject will improve your options or simply divide your attention.

For students who are choosing between 10 and 12 units, the best pattern is not necessarily the one with the most subjects. It is the one that keeps your future options open while giving you enough time to perform well in the courses that matter.

Once your unit load is settled, the next decision is whether your individual subject choices give you the knowledge and preparation required for your intended university pathway.