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Understanding the IB
IB HL vs SL: Key Differences and How to Choose
By Constantin Mardoukhaev · Reviewed by Axiom Academic's academic team
In the IB Diploma, Higher Level (HL) and Standard Level (SL) are the two depths at which each subject is taught: HL is broader and takes around 240 teaching hours, while SL is more focused at around 150 hours. Each student studies six subjects, typically three at HL and three at SL, and both levels are graded on the same 1–7 scale.
What HL and SL actually mean
Every subject in the IB Diploma Programme is studied at one of two levels: Higher Level (HL) or Standard Level (SL). The difference is depth and time, not prestige. HL courses cover more material in greater detail and usually include an extra assessment component, while SL covers the core of the same subject in fewer hours.
- HL: around 240 teaching hours, broader and deeper content, often additional options.
- SL: around 150 teaching hours, focused on the essential syllabus.
How many of each do you take?
Each student studies six subjects, one from most subject groups, plus the three core elements (Theory of Knowledge, the Extended Essay and CAS). The standard split is three HL and three SL, though many schools allow four HL and two SL. All subjects use the same 1–7 scale, so an HL 6 and an SL 6 contribute equally to your total out of 45.
HL vs SL at a glance
| Aspect | Standard Level (SL) | Higher Level (HL) |
|---|---|---|
| Teaching hours | ~150 | ~240 |
| Content | Core syllabus | Core + additional depth |
| Grading | 1–7 | 1–7 |
| Typical number | 3 subjects | 3 subjects |
| Best for | Breadth, balanced workload | Strengths and university prerequisites |
How to choose
Pick HL for the subjects that are strengths, that you enjoy, and, crucially, that your target universities require. Many degrees specify HL subjects (for example HL Mathematics or HL Chemistry for engineering or medicine), so check entry requirements before finalising your choices. Keep at SL the subjects you need for breadth but don't plan to pursue.
If a subject feels too demanding at HL, switching down to SL early in the first year is common and usually straightforward. Our IB subject tutors can help you decide level by level, or support a specific HL course where the workload jumps.
Frequently asked questions
Can I take four HL subjects?
Yes, many schools let students take four HL and two SL. It increases the workload, so it is best reserved for strong subjects or specific university requirements.
Do universities prefer HL subjects?
Universities set requirements at HL for the subjects that matter to a degree (for example HL Chemistry for medicine). Beyond those prerequisites, a balanced three HL and three SL profile is completely standard.
Can I switch from HL to SL?
Yes, usually early in the first year (DP1). Switching down is common and rarely a problem; switching up later is harder because of the additional content already covered at HL.
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