Chemistry, but only just. In the 2025 HSC, Chemistry scaled to a mean of 32.0 out of 50 on a one-unit basis and Physics to 31.0. That one-mark difference is small enough that it should not decide your subject choice. The far more useful finding, when you ask whether Physics or Chemistry scales better, is how big the gap is between both of them and the science most students actually take: Biology, at 26.2.
These figures come from the official UAC Report on the Scaling of the 2025 NSW HSC, Table A3. Scaling is recalculated each year, so use them for relativities rather than as a forecast of your own result.
How did every HSC science course scale in 2025?
| Course | Students (2025) | Mean HSC mark | Mean scaled mark |
|---|---|---|---|
| Chemistry | 10,369 | 37.6 | 32.0 |
| Science Extension | 855 | 37.6 | 32.0 |
| Physics | 8,817 | 37.0 | 31.0 |
| Biology | 20,710 | 36.7 | 26.2 |
| Earth and Environmental Science | 2,678 | 37.3 | 22.8 |
| Investigating Science | 3,292 | 37.8 | 20.5 |
Marks are on a one-unit basis out of 50. Source: UAC Report on the Scaling of the 2025 NSW HSC, Table A3.
Notice the third column. The mean HSC marks are remarkably similar across all six courses, from 36.7 to 37.8. The mean scaled marks range from 20.5 to 32.0. That contrast is the clearest illustration of what scaling does that you will find anywhere in the report.
Why is the Chemistry and Physics gap so small?
Because the two courses attract almost the same kind of student. Chemistry and Physics are both taken overwhelmingly by students who are also doing Mathematics Advanced or Extension, and scaling measures the academic strength of a course’s candidature across everything those students study. Two courses drawing from the same pool will scale to nearly the same place.
A one-mark difference on a 50-point scale, spread across two units, is not something you can plan around. It is also not stable: the gap between these two courses shifts a little each year depending on who enrols. Anyone telling you to pick Chemistry over Physics for the scaling is giving you advice with no useful margin in it. Our guide to reading the HSC scaling report explains why these year-to-year wobbles happen.
Why does Biology scale so much lower than Physics and Chemistry?
This is the gap that actually matters, and it is nearly five marks. Biology had 20,710 students in 2025, more than double the Physics candidature and twice the Chemistry one. It is the science that students take when they want a science but do not want a heavily mathematical one, so its cohort is broader and includes many students not doing higher-level maths.
Nothing about that makes Biology an easy course or a bad choice. It says that the average Biology student, across their whole HSC, sits lower than the average Chemistry student. Scaling then reflects that. A student in the top band of Biology still ends up with a very strong scaled mark; the mean simply sits lower.
Where do the sciences sit against other HSC subjects?
Placing the 2025 science figures alongside other major courses puts the debate in perspective:
- Mathematics Extension 1: 39.7
- English Advanced: 32.8
- Chemistry: 32.0
- Mathematics Advanced: 31.9
- Economics: 31.4
- Physics: 31.0
- Biology: 26.2
- Modern History: 25.0
- Business Studies: 23.9
- Earth and Environmental Science: 22.8
- Investigating Science: 20.5
Chemistry, Mathematics Advanced and Physics land within one mark of each other, and English Advanced sits above all three. The idea that the sciences are a shortcut to a high ATAR does not survive contact with the table. If you want the full ranking, see our list of the highest scaling HSC subjects and the companion piece on the worst scaling HSC subjects.
Does Science Extension scale as well as Chemistry?
In 2025 it matched it exactly, at 32.0. There is a structural reason for this. UAC calculates the scaled mean for Science Extension from how those students perform in their 2-unit sciences, so it is anchored to Biology, Chemistry, Earth and Environmental Science, Investigating Science and Physics rather than being scaled in isolation. We go deeper on this in our post on whether Science Extension scales well.
Which is harder, Physics or Chemistry?
They are hard in different ways, which is more useful to know than the scaling difference.
Physics rewards mathematical fluency and the ability to reason from a small number of principles. Students who are comfortable rearranging equations and thinking in models generally find it manageable. Students who are not tend to find it brutal, because there is nowhere to hide behind memorised content.
Chemistry rewards volume and precision. There is significantly more to hold in memory, particularly in the organic and acid-base modules, and the calculations demand careful, methodical setting out rather than mathematical sophistication. Our HSC workload guide compares content loads across courses.
Should you take both Physics and Chemistry?
Many strong students do, and it is a reasonable combination if you are also doing Mathematics Advanced or Extension. Be honest about the load, though. Both courses are content-heavy, both have depth studies, and both examine practical skills. Together they can consume most of a student’s study week. There is some genuine overlap, since the quantitative habits Physics builds transfer usefully to Chemistry calculations, but the content itself barely overlaps at all, so you are carrying two full syllabuses rather than one and a half.
Here is an illustrative comparison we see play out most years. Student A takes Physics, Chemistry, Mathematics Extension 1 and English Advanced, spreads thin, and finishes mid-cohort in all four. Student B takes Chemistry, Biology, Mathematics Advanced and English Advanced, has the capacity to go deep, and finishes near the top of each. Student B usually ends up with the better ATAR, despite the “lower scaling” subject list, because scaled marks depend on where you sit within the cohort, not just which cohort you joined.
What should actually drive the decision?
In order: what you are good at, what you will keep working at for two years, and what your intended university course requires. Some engineering and physical science degrees assume Physics or Chemistry, and some health degrees assume Chemistry. Check the assumed knowledge for your target courses before you choose, because that constraint is real in a way a one-mark scaling difference is not.
Our subject selection guide walks through the whole decision, and if exams are closer than subject selection for your family right now, the 2026 HSC exam timetable sets out the dates you are working towards.
How can tutoring help in Physics and Chemistry?
These are the two subjects where a small conceptual gap compounds fastest. A student who never really understood mole calculations or free-body diagrams in Year 11 will keep paying for it through Year 12, and classroom pace rarely allows for going back. One-to-one work is well suited to finding and closing those specific gaps rather than re-teaching whole modules.
Our HSC tutoring in Sydney and online tutoring both cover Physics, Chemistry and Biology with tutors who have sat these courses recently. You can book your first lesson today and see whether it fits before committing further.
Frequently asked questions
Does Physics or Chemistry scale better in the HSC?
Chemistry scaled marginally higher in 2025, with a mean scaled mark of 32.0 out of 50 against 31.0 for Physics. The one-mark difference is too small and too variable year to year to justify choosing one over the other on scaling grounds.
Does Biology scale badly?
Biology scaled to a mean of 26.2 in 2025, around five marks below Physics and Chemistry. That reflects the broader academic profile of its much larger cohort, not the difficulty of the course. A top Biology result still scales strongly.
Which HSC science scales the highest?
Chemistry and Science Extension were level at 32.0 in 2025, followed by Physics at 31.0, Biology at 26.2, Earth and Environmental Science at 22.8 and Investigating Science at 20.5.
Will these scaling figures be the same for the 2026 HSC?
No. UAC recalculates scaling every year from that year’s cohort, so the exact numbers will differ. The ordering of the science courses has been fairly stable, so the relativities are a reasonable guide.
Is it worth taking Physics and Chemistry together?
It works well for students who are also doing higher-level maths and can sustain two content-heavy courses. If taking both means finishing mid-cohort in each rather than near the top of fewer subjects, it is usually the wrong trade.