Overview
The best IB subject combination is the one that satisfies the six-group structure while including the higher-level (HL) subjects your target degree requires — everything else is optimisation around that core rule. Unlike A-Levels, the IB does not let you pick any three subjects freely: you take one from each of six groups, choose three (sometimes four) at HL, and the rest at standard level (SL). Within those constraints there is real room to shape a profile for medicine, engineering, economics or a broad liberal-arts application, and getting your HL choices right in July matters far more than chasing "easy" options.
The rules you have to work within
Every IB Diploma follows the same skeleton: one subject from Group 1 (Studies in Language and Literature), Group 2 (Language Acquisition), Group 3 (Individuals and Societies), Group 4 (Sciences), Group 5 (Mathematics), and either a Group 6 arts subject or a second subject from Groups 1–4. You then designate three at HL and three at SL (some students do four HL). Maths is compulsory, and you choose between [Maths AA and Maths AI](/blog/ib-maths-aa-vs-ai-which-to-choose) — a decision that itself can gate certain degrees. Work out your HL trio first, because that is what universities read most closely.
| Group | Choose from | Common HL picks |
|---|---|---|
| 1 — Language & Literature | Your strongest language | English (Lang & Lit or Literature) |
| 2 — Language Acquisition | A second language | Often kept at SL |
| 3 — Individuals & Societies | Economics, History, Psychology, Geography… | Economics, History |
| 4 — Sciences | Biology, Chemistry, Physics… | Chemistry, Physics, Biology |
| 5 — Mathematics | Maths AA or Maths AI | Maths AA HL for STEM |
| 6 — Arts or second from 1–4 | Visual Arts, or extra science/humanity | A second science for medicine |
HL choices are the ones that count
For the IB Diploma Programme, universities set entry requirements primarily around HL subjects and total points, so your three HLs are the strategic decision. Aim for HLs that are (a) required by your target course, (b) subjects you can realistically score 6 or 7 in, and (c) a balanced load rather than three of the most content-heavy sciences at once. A common mistake is stacking HL Chemistry, Physics and Maths AA "to look serious" and then dropping to 4s and 5s under the workload — a lower HL count of strong grades beats an overloaded set of mediocre ones.
Combinations by degree target
Medicine and dentistry: HL Chemistry is almost universally required, usually with HL Biology, and often a strong Maths; check each medical school, as requirements are strict. Engineering: HL Maths AA and HL Physics are the backbone, with Chemistry useful for some branches. Economics and business: HL Economics with HL Maths (AA preferred by some universities) and a strong essay subject signals quantitative and analytical range. Law, humanities and liberal arts: a HL essay-and-analysis mix — English, History, Economics or Psychology — plays to the IB's breadth and to holistic US admissions. When unsure of your degree, keep one science and Maths AA at a workable level to avoid closing STEM doors.
Balance the workload, not just the prestige
Because the IB runs six subjects plus the Extended Essay, TOK and CAS simultaneously, sustainability is a real constraint. Pair demanding HLs with SLs you can manage, and be honest about your writing-versus-calculation strengths across the two years. You can pressure-test how each subject is actually marked using [free IB syllabus courses](/ib/courses) and [instant marking against real markbands](/mark) before you commit — the felt experience of a subject's assessment style tells you more than a difficulty ranking. For the difficulty of specific subjects, our [SL vs HL guides](/ib) break down each one.
Frequently asked questions
This section covers Frequently asked questions — what IB examiners reward most often in past papers and coursework.
How many HL subjects should I take?
Most students take three HL and three SL subjects; some take four HL. Four HLs increase the workload significantly, so only do it if a specific university or course expects it, or if you are confident you can maintain high grades across all four.
Which IB subjects are "best" for university?
There is no universally best set — the best subjects are the ones your target degree requires at HL and that you can score highly in. For STEM that usually means HL Maths and sciences; for humanities, a strong essay-subject mix. Match subjects to the course, then to your strengths.
Do I have to take a science and a language?
Yes, in the standard diploma. You take one Group 4 science and one Group 2 language among your six subjects, though either can be at SL. The Group 6 slot can be swapped for a second subject from Groups 1–4 if you prefer, for example a second science.
Does HL Maths AA or AI matter for my degree?
It can. Many STEM and economics courses prefer or require Maths AA, especially at HL, because of its calculus focus, while AI suits data- and modelling-oriented paths. Check target-course requirements before choosing — see our AA vs AI guide.