IB HL vs SL: How to Choose Your Higher Level Subjects

Choosing your IB subjects, and which three to push to Higher Level, is one of the most consequential academic decisions you will make. Get it right and your HL subjects become your strongest cards for university applications. Get it wrong and you spend two years grinding through content that kills your predicted grades or closes doors you needed open.

IB Higher Level (HL) subjects need a minimum of 240 teaching hours and go considerably deeper than Standard Level (SL) at 150 hours. Every Diploma student takes exactly three HL and three SL subjects. The right HL choices depend on your university targets, your genuine strengths, and a realistic look at the workload you can handle across six subjects at once.

This guide walks through how the choice actually works, what drives good decisions, the most common mistakes, and how to sanity-check your subject combination before you commit.

What HL and SL actually mean

The IB Diploma Programme, designed by the International Baccalaureate Organization (IBO), requires every student to study six subjects from six different groups: their first language, a second language, a social science or humanities, a science, mathematics, and an arts subject or a second course from another group.

Within those six, you choose three to study at Higher Level and three at Standard Level.

According to the IBO official programme standards, HL subjects have a minimum of 240 teaching hours over two years; SL subjects have 150. The extra 90 hours shows up as additional topics, greater depth, and longer external assessments. A typical HL paper is more demanding than its SL equivalent, and internal assessment criteria at HL usually require a higher level of independent analysis.

This is not a marginal gap. In many subjects, the HL and SL courses share a common core but HL adds several extra option topics plus extensions that SL students never see. In Maths AA (Analysis and Approaches), for example, the HL course adds complex numbers, proof by induction, and further calculus that simply do not appear at SL. The IBO publishes the full breakdown on the IB Diploma Programme curriculum page.

The table below summarises the headline differences:

The five things that should drive your HL choices

1. What your target universities require

This is the most important filter, and students often check it too late. Many UK universities include specific HL subject requirements in their entry criteria, particularly for competitive or vocational programmes.

Medicine is the clearest example: most UK medical schools state in their entry requirements that applicants should hold Chemistry and Biology at HL as the standard science combination. Engineering programmes at selective universities frequently ask for Maths HL (or Maths AA HL specifically) and often Physics HL. Law, PPE and economics degrees at some Russell Group universities do not mandate specific HL subjects but respond well to history, economics or a humanity at HL.

If you have a target degree, look up the admissions pages of every university you might apply to. Note the HL requirements, not just the overall grade requirements. This step alone eliminates many wrong choices.

2. Your genuine strengths

Universities want to admit students who perform well. A 7 at HL in a subject you are strong in is worth far more to an application than a 4 at HL in a subject you struggled with because you thought it looked impressive.

This matters especially because the IB is a marathon. You are studying six subjects simultaneously for two years while writing an Extended Essay, completing an Internal Assessment in multiple subjects, engaging with Theory of Knowledge, and fulfilling CAS hours. The HL subjects you choose will demand the most from you throughout this process. Taking three HL subjects that genuinely interest you and that you have a track record of performing well in is not the easy path out; it is the strategically sound one.

3. HL workload and your overall balance

Some HL courses carry a heavier independent workload than others, separate from teaching hours. Chemistry HL and Biology HL have substantial Internal Assessments and paper-based recall demands. History HL requires analysis-heavy essay writing across Paper 1, 2 and 3. Maths AA HL involves a genuinely difficult exploration IA.

Your three HL choices together form a combined load. A combination of, say, Chemistry HL, Biology HL and History HL alongside three SL subjects is a heavy programme. A combination of Chemistry HL, English A HL and Business Management HL tends to be more varied in its demands. Neither is wrong, but you should go into your choice aware of how the workloads compound.

4. Which subjects your school teaches particularly well at HL

This is under-discussed. The quality of teaching at HL matters, because HL goes into territory that requires a confident, knowledgeable teacher to navigate the extension topics and guide students through the Internal Assessment properly. If your school's Chemistry HL teacher is exceptional and Physics HL is taught by someone in their first year, that is relevant information. Talk to students in the year above you, honestly.

5. Whether the exam format plays to your strengths

Some HL subjects are heavily essay-based (History, English A, Economics), some are calculation-heavy (Maths AA, Physics, Chemistry), and some involve project or performance-based assessment (Visual Arts, Music, Theatre). This is not just about ability; it is also about what type of studying you find sustainable over two years. If writing long analytical essays energises you, history or English HL is a natural fit. If you find extended written work draining, stacking three essay-heavy HLs is a recipe for burnout.

Common HL combinations by university pathway

These are rough patterns, not rules. Always verify against specific entry requirements.

Medicine (UK): Chemistry HL + Biology HL are nearly universal requirements. The third HL is often Maths (AA or AI) or Physics. Some schools accept Psychology or another science.

Engineering: Maths AA HL is standard. Physics HL is almost always required or strongly preferred. The third HL varies (Chemistry, Computer Science, or an essay subject for breadth).

Economics, PPE, Social Sciences: Economics HL or History HL is common. Maths AA or AI HL is increasingly valued for quantitative programmes. English A HL adds strength for humanities-heavy courses.

Law: No fixed requirements, but History HL and English A HL are natural fits. Strong Maths AA HL or Economics HL can differentiate applicants for law programmes with quantitative components.

Computer Science / Technology: Maths AA HL is the core anchor. Computer Science HL strengthens the application directly.

These patterns exist because universities have designed their courses to build on specific prior knowledge. Choosing HL subjects that align with your intended degree means your Year 1 university content builds on what you already studied in depth, rather than starting from scratch.

The mistakes students most often make

Taking HL subjects to impress rather than to perform. A 5 in Maths AA HL does not outrank a 7 in Maths AI SL in the eyes of most admissions offices (unless Maths AA HL is a specific requirement). Choose HL where you will get strong grades.

Not checking university requirements until it is too late. Some students realise in Year 2 that their target medical school wanted Chemistry HL and they took it at SL. By that point there is nothing to do.

Choosing HL because your friends are. Subject choices feel social in Year 1. They are not. Your combination needs to serve your targets, not match your peer group.

Ignoring the extended content entirely. Students sometimes pick an HL subject without reading what the additional HL-only topics involve. The Maths AA HL extension covers calculus techniques and complex numbers that many students find genuinely difficult. Know what you are committing to.

Underestimating SL. SL subjects still require two years of teaching, internal assessments and external exams. They are not trivial. Your three SL choices still matter.

---

The hardest part of choosing HL subjects is that you are making a two-year commitment at a point in your life when you do not yet fully know what you are capable of academically. That uncertainty is normal. What reduces it is getting as much specific information as possible before you choose: your university targets, your Year 10 or GCSE results in relevant subjects, and honest conversations with teachers and students in the year above.

This is where many students realise how little structure they have for their studying as a whole. Tracking six subjects across two years, knowing which topics from Year 1 to revisit in Year 2, and working out what to focus on each week is a genuine organisational challenge. Most students try to manage it manually and find that the sheer admin of keeping on top of everything is almost as draining as the content itself.

Root is an adaptive tutor that was built by an IB student specifically for this problem. It learns how your brain works, spots exactly what you are not understanding, and remembers it across sessions, so you never have to guess what to study next. It also manages your study plan automatically: on the free plan it runs 2 exam-style practice tests a week with examiner-style per-question marking, and a revision mode that finds your weak topics and brings them back at the right intervals until they actually stick. You do not need to know what to study; Root works that out for you. Here is a full breakdown of what Root does, and you can set up a free account in a couple of minutes.

(Root is our product, and we are describing it honestly: it was built for the IB and also supports GCSE, IGCSE and A Level.)

---

Before you finalise your choices: a three-question check

1. Have you checked the HL requirements for every university and course you might apply to? Not just your first choice, but your realistic range.
2. Are your three HL subjects ones where you have a track record of strong performance or genuine enthusiasm? Or are you picking them because they sound impressive?
3. Does your combination give you a balanced load, or have you stacked three of the most workload-intensive HLs together?

If the answer to all three is yes, your combination is probably sound. If any answer is no, it is worth one more conversation with your school's IB coordinator before you commit.

Your HL subjects do not define you, but they do shape your university options and your experience of the next two years. It is worth getting them right.

---

For more on managing the IB as a whole, see our guide to studying for the IB and building an IB revision timetable. If you are later choosing how to revise for specific subjects, study techniques that actually work and active recall are good starting points.