IB Diploma Explained — HL, SL, IA, TOK and the 45-Point Scale

What is the IB Diploma?

The International Baccalaureate Diploma Programme (IB DP) is a two-year pre-university qualification taken by students aged 16–19, typically as an alternative to A-Levels. It is offered by IB World Schools in over 160 countries and is accepted by universities worldwide, including all UK universities.

Unlike A-Level (where you typically study three subjects in depth), the IB Diploma requires you to study six subjects simultaneously, plus three core components. This breadth is its defining feature — and its biggest challenge.

The six subject groups

IB students choose one subject from each of six groups:

1. Studies in Language and Literature — e.g. English A Literature, English A Language & Literature
2. Language Acquisition — a second language (e.g. French B, Spanish ab initio)
3. Individuals and Societies — e.g. History, Economics, Geography, Psychology
4. Sciences — e.g. Biology, Chemistry, Physics, Computer Science
5. Mathematics — Analysis and Approaches (AA) or Applications and Interpretation (AI), each at HL or SL
6. The Arts — e.g. Visual Arts, Music, Theatre. Students who do not want an arts subject can replace this with a second subject from groups 3 or 4.

Higher Level (HL) and Standard Level (SL)

This is one of the most important structural features of the IB. Each of your six subjects is taken at either Higher Level (HL) or Standard Level (SL). You must take exactly three HL subjects and three SL subjects.

• HL subjects cover more content, go into greater depth, and carry more teaching hours (240 hours over two years, vs 150 hours for SL). HL exams are longer and include questions that require greater analytical depth.
• SL subjects cover the core content of the syllabus at a less demanding level. They are still serious qualifications — SL grades contribute to your Diploma score and university applications.

Choosing your HL subjects is one of the most important decisions you make when starting the IB. Pick subjects you are genuinely strong in and that align with your intended university course. Most universities specify which subjects they require at HL (e.g. a medicine applicant typically needs Biology and Chemistry at HL).

How each subject is graded

Every IB subject is graded on a scale of 1 to 7, where 7 is the highest. A grade of 4 is the minimum passing grade per subject. Your grade is based on a combination of:

• External assessment (EA) — exams sat in May or November of your second year, marked by IB examiners worldwide.
• Internal Assessment (IA) — coursework produced during the two-year course, assessed by your teacher and moderated externally by the IB. The IA is subject-specific: a Biology IA is a scientific investigation; a History IA is a historical investigation essay; an Economics IA is a portfolio of three commentaries.

The weighting between EA and IA varies by subject but is typically 75–80% external / 20–25% internal.

The three core components

In addition to your six subjects, every IB Diploma student must complete three core components:

Theory of Knowledge (TOK)

TOK is a compulsory philosophy-of-knowledge course. You explore questions like "How do we know what we know?" and "What counts as evidence across different disciplines?" TOK is assessed by an essay (1,600 words, submitted externally) and a class presentation. It is graded A–E and contributes bonus points to your Diploma total.

The Extended Essay (EE)

The Extended Essay is a 4,000-word independent research paper on a subject of your choice (usually one of your six IB subjects). It is supervised by a teacher at your school and submitted externally. Like TOK, it is graded A–E.

Creativity, Activity, Service (CAS)

CAS requires you to engage in creative activities, physical activities, and service to others throughout your two years. There are no grades — CAS is pass/fail, but failure to complete it means you do not receive the Diploma. Schools have varying requirements for what counts as CAS.

The 45-point scale — how your total is calculated

Component	Maximum points
Six subjects (max 7 points each)	42 points
TOK + Extended Essay bonus points	3 points
Total maximum	45 points

The bonus points from TOK and the EE are awarded on a combined matrix. Scoring A in both gives you 3 bonus points; A+B or B+A gives 2; lower combinations give 1 or 0. This makes the TOK essay and EE strategically important — they can add 3 points to your total without requiring any extra subject study.

The minimum score to be awarded the Diploma is 24 points, subject to meeting several other conditions:

• No grade below 3 in any HL subject
• No grade below 2 in any SL subject
• No grade of N (not submitted) in TOK, EE, or CAS
• No grade of E in TOK or EE
• Combined HL grades of at least 12 (e.g. 4+4+4)

How does IB compare to A-Level?

IB is broader but A-Level goes deeper. A student taking A-Level Chemistry will spend more time on Chemistry than an IB HL Chemistry student. For subjects where depth matters most at degree level (e.g. Mathematics, Sciences), some university departments note this and may offer bridging courses. For subjects where breadth and independent thinking matter (e.g. Humanities, Social Sciences), IB students are often very well prepared.

UCAS points for IB: 45 points = 720 UCAS tariff points; 38 points ≈ 600 UCAS tariff points. However, most competitive universities do not use tariff points and consider the IB score and HL grades directly.

Revision for IB exams

IB exams are sat in a concentrated period in May (or November for southern hemisphere schools), meaning you are revising six subjects simultaneously. Prioritise your HL subjects — they carry more marks per subject (7 points vs 7 for SL, but the content is harder and the questions more demanding). ExamPass.ai supports IB subjects with AI-generated practice questions and mock papers, including subject-specific question types matched to IB exam conventions.