Overview
For the IB Diploma Programme, take HL Physics if you are heading into engineering, physics, or a maths-heavy STEM degree and you are comfortable pushing your algebra and problem-solving further; take SL if you want a solid grounding in physics for breadth without the heaviest maths load. The honest answer depends on two things — your university plans and how confident you feel with multi-step maths. This guide compares the two levels precisely so you can decide with evidence rather than rumour.
What's the same at SL and HL
Both levels of the 2025 IB Physics syllabus share the same five themes:
- A — Space, time and motion (kinematics, forces, energy, momentum)
- B — The particulate nature of matter (thermal physics, gases, current)
- C — Wave behaviour (oscillations, waves, interference, resonance)
- D — Fields (gravitation, electric and magnetic fields)
- E — Nuclear and quantum physics (atomic structure, radioactivity, fission/fusion)
Both levels also do the same scientific-investigation internal assessment (IA) — an independent experimental report marked against identical criteria — and both are supplied with a data booklet of equations and constants in the exam, so neither level is a memory test of formulae. The difference is not what you study at the theme level; it is how deep you go and how much maths you use to get there.
What HL adds
For the IB Diploma Programme, hL covers all five shared themes in greater depth and adds HL-only content that SL never touches, including:
- A.4 Rigid body mechanics — torque, moment of inertia, angular momentum
- A.5 Special relativity — time dilation, length contraction, spacetime
- B.4 Thermodynamics — the laws of thermodynamics, entropy, engine cycles
- D.4 Electromagnetic induction — flux, induced EMF, generators
- E.2 Quantum physics — photoelectric effect, wave-particle duality, energy levels
On top of these extra topics, HL threads more mathematical derivations through the shared material — you are more often asked to derive a result, not just apply a given equation.
| SL | HL | |
|---|---|---|
| Content | 5 shared themes | Same 5 themes in more depth + HL-only topics |
| Teaching hours | ~150 | ~240 |
| Exam length | Shorter papers | Longer papers, harder multi-step questions |
| Maths / derivation load | Applying equations from the data booklet | More algebra, more derivations, more chained problem-solving |
| IA | Same scientific-investigation IA | Same scientific-investigation IA |
How much harder is HL Physics?
For the IB Diploma Programme, hL is a meaningful step up, and it is honest to say so. The extra roughly 90 teaching hours are not padding — they buy genuinely more demanding material. Two things drive the difficulty:
- Maths. HL Physics is the more maths-heavy choice. You will rearrange and combine equations more aggressively, work through derivations, and handle problems where the physics insight is only half the battle — the algebra is the rest.
- Multi-step problems. HL exam questions more often chain several concepts together: a single question might link forces, energy, and fields, expecting you to carry a result from one part into the next without a prompt.
If you enjoy that kind of layered problem-solving, HL is rewarding. If maths is where you struggle, HL will amplify that pressure. Your comfort with maths is the single best predictor of how HL Physics will feel.
The HL Physics + HL Maths pairing for engineering
For the IB Diploma Programme, for engineering applicants, HL Physics paired with HL Maths (usually Analysis & Approaches) is one of the most common and best-regarded combinations. The two reinforce each other: the calculus and algebra you build in HL Maths directly support the derivations in HL Physics, and engineering degrees expect that mathematical maturity from day one. If engineering is your goal, treat this pairing as the default to aim for and only step down after checking specific university requirements.
University requirements
For the IB Diploma Programme, university science and engineering courses usually prefer or require HL Physics — this is especially true for:
- Physics degrees
- Engineering — mechanical, electrical, aerospace, civil
- Some computer-science and maths courses
SL Physics is often accepted for breadth or for degrees where physics is not the core subject, but for a physics or engineering path it is frequently insufficient on its own. Requirements vary widely between countries and universities, so check the exact entry offers for your target courses early — do not rely on general assumptions or what a friend was told.
Who should take HL vs SL
For the IB Diploma Programme, take HL Physics if you: - Plan to study physics, engineering, or a maths-heavy STEM degree - Are comfortable with — or want to strengthen — multi-step maths - Are pairing it with HL Maths - Enjoy deriving results, not just plugging into formulae
Take SL Physics if you:
- Want a strong physics foundation for breadth in your diploma
- Are stronger in other subjects and want to balance workload
- Are heading into a field where physics supports but does not lead (some life sciences, architecture, design)
- Prefer applying equations over deriving them
How to decide
This section covers How to decide — what IB examiners reward most often in past papers and coursework.
- Start from the destination. List target degrees and read their actual entry requirements. If they say HL Physics, that settles it.
- Be honest about maths. If HL Maths already worries you, stacking HL Physics on top is a heavy load — plan realistically.
- Try the real thing. Attempt an HL question set and an SL set on the same topic and compare how each feels.
- Talk to your teacher. They have seen how students with your profile cope at each level.
How MarkScheme helps
MarkScheme lets you test the difference before you commit. Work through the free [IB Physics SL course](/ib/courses/physics-sl) and [HL course](/ib/courses/physics-hl) to feel the depth gap, then drill real exams with the [SL past papers](/blog/ib-physics-sl-past-papers-guide) and [HL past papers](/blog/ib-physics-hl-past-papers-guide) guides. When you want to know whether your working would actually earn the marks, [get an answer marked](/mark) against examiner criteria. For the wider picture, see [how to get a 7 in IB Physics](/blog/ib-physics-how-to-get-a-7) and the [IB guides hub](/guides/ib).
Frequently asked questions
This section covers Frequently asked questions — what IB examiners reward most often in past papers and coursework.
Is HL Physics hard?
It is one of the more demanding HL sciences, mainly because of the maths and the multi-step problem-solving — not because the concepts are impossible. Students who are comfortable with algebra and enjoy layered problems tend to cope well; those who struggle with maths feel the pressure more.
Do I need HL Physics for engineering?
Usually, yes — most engineering degrees prefer or require HL Physics, often alongside HL Maths. But requirements differ by university and country, so check the specific offers for your target courses rather than assuming.
What extra topics does HL cover?
HL adds rigid body mechanics (A.4), special relativity (A.5), thermodynamics (B.4), electromagnetic induction (D.4), and quantum physics (E.2), plus more mathematical derivations across the shared themes.
Is the IA different at HL and SL?
No — both levels complete the same scientific-investigation internal assessment, marked against the same criteria. The difference between levels is in the taught content and the exams.
Can I take SL Physics and still do a science degree?
For some life-science, architecture, or design routes, SL Physics can be enough for breadth. For physics and engineering specifically, HL is usually expected — always verify against real entry requirements.