UK Exam Boards vs the IB: A Sixth Provider Competing Inside UK Schools

Unlike every other article in this cluster, the International Baccalaureate isn't a comparison from abroad — it's a live alternative sitting inside UK sixth forms right now, chosen instead of A-levels by around 87 UK schools. The IB is run entirely independently of the UK's five awarding bodies, is not regulated by Ofqual, and is built on a different philosophy: breadth across six subjects for every student, rather than depth in a small number a student chooses.

Every other country in this cluster is a genuine international comparison — a different national system, examined from outside. The IB is different: a UK parent researching sixth-form options may find it listed on a school's own website as a real, present-tense alternative to A-levels. This article treats it on those terms — as a sixth provider a UK school can pick, run by a body entirely outside the five-board system.

Who runs the IB, and why it isn't a UK exam board

The International Baccalaureate Organization (IBO) is a non-profit foundation based in Geneva, Switzerland, founded in 1968. It designs, examines and awards the IB's four programmes worldwide, of which the Diploma Programme (DP), for 16- to 19-year-olds, is the one that competes directly with UK A-levels.

The IBO has no relationship to AQA, Pearson Edexcel, OCR, WJEC/Eduqas or CCEA, and its qualifications are not regulated by Ofqual. A UK school offering the IB Diploma is opting entirely out of the domestic awarding-body system for that qualification — its students sit IBO-set exams, marked by IBO-appointed examiners, under IBO's own quality-assurance framework, not a UK regulatory one.

How many UK schools actually offer it

The IB remains a minority route in the UK. As of the mid-2020s, around 87 UK schools were authorised to teach the IB Diploma Programme, out of roughly 129 UK schools offering any IB programme in total. The great majority of Diploma-authorised schools are independent schools; a smaller number are UK state schools and sixth-form colleges, concentrated particularly in England's South East. By comparison, the number of UK schools offering A-levels runs into the thousands — the IB Diploma is a genuine but small-scale alternative, not a mainstream one.

What an IB Diploma student actually sits

The IB Diploma is built around breadth by design, in deliberate contrast to A-level specialisation:

• Six subjects, one from each of six subject groups (first language, second language, individuals and societies, sciences, mathematics, and an elective — often an arts subject), each studied at Higher or Standard Level.
• Theory of Knowledge (TOK) — a compulsory course examining how knowledge itself is constructed, assessed through an essay and an exhibition.
• The Extended Essay (EE) — an independently researched 4,000-word essay in a subject of the student's choosing, externally assessed.
• Creativity, Activity, Service (CAS) — a non-examined but compulsory requirement for extracurricular engagement.

Assessment blends external written examinations (the majority of most subjects' marks) with internal assessment — coursework or practical tasks, marked by the student's own teachers and then externally moderated by the IBO — a structure that runs through every subject rather than varying subject-by-subject the way UK GCSE and A-level coursework does.

By contrast, a UK A-level student typically studies three or four subjects, entirely externally examined in most cases, with no compulsory breadth requirement, no extended essay, and no service component built into the qualification itself.

Not the only alternative: where Cambridge International fits

The IB isn't the only qualification a UK school can choose instead of A-levels. Cambridge International, part of Cambridge University Press & Assessment — the same group that owns OCR — offers its own sixth-form qualification, Cambridge International AS & A Levels, taught in a smaller number of UK schools alongside a much larger international network. Unlike the IB, Cambridge International A Levels are structurally close cousins of UK A-levels: single-subject, typically studied in a similar three-or-four-subject combination, without the IB's compulsory breadth requirement or its Theory of Knowledge and Extended Essay components. That makes Cambridge International a genuinely different kind of alternative to A-level than the IB is — same narrow, depth-first philosophy as UK boards, just examined by a different body — where the IB represents a philosophically distinct, breadth-first model. (See UK exam boards vs Cambridge International for the fuller comparison.)

A worked example: choosing between the two

Consider a student who knows by Year 11 that they want to study Engineering at a UK university. Under A-levels, they would typically take Maths, Further Maths and Physics — three subjects, all directly relevant, with no obligation to keep studying English or a humanities subject once GCSEs are done. Under the IB Diploma, the same student would still need to select one subject from each of the six groups, meaning they'd study Maths and Physics at Higher Level alongside a compulsory language, a humanities or social-science subject, and an arts or additional science option at Standard Level — plus the Extended Essay, Theory of Knowledge and CAS regardless of how sure they are about Engineering. Universities reading either result would look for strong Higher Level or A-level grades in the directly relevant subjects; the practical difference is how much of the student's final two years of school time goes toward subjects outside that direct line, which the IB deliberately protects and A-level does not.

UK exam boards vs the IB Diploma, at a glance

Why so few UK schools offer it

Given the IB's international reputation, it's worth asking why only a minority of UK schools have taken it up. Part of the answer is resourcing: running the IB Diploma alongside A-levels means timetabling, staffing and examining two structurally different qualifications rather than one, which is a heavier lift for a state school working within a fixed budget than for an independent school with more flexibility. Part of it is also familiarity — university admissions tutors, careers advisers and most parents in the UK have spent their whole working lives inside the A-level system, so a school choosing the IB is choosing to explain an unfamiliar qualification to its own community every year, even though UK universities are well practised at reading IB results fairly. This is why IB Diploma schools in the UK skew independent and skew toward areas with either an international-facing population or a long-standing IB tradition, rather than being evenly spread across the country the way A-level provision is.

What the contrast reveals about the UK

The IB's presence inside the UK is a useful reminder that "the UK exam system" is not a closed system — schools are free to opt into an entirely different, internationally governed qualification for their sixth form, and a meaningful (if small) number do. Its enduring appeal for the schools that choose it is structural: breadth is compulsory rather than optional, and every Diploma student graduates having written an extended essay and studied the theory of knowledge, regardless of which six subjects they picked.

That the IB and A-levels can sit side by side in the same country, assessed by entirely separate bodies under entirely separate rules, and still be treated as broadly interchangeable by UK universities, says something about how UK higher education admissions actually work: it reads outcomes, not organisational pedigree. A strong grade profile from either system opens broadly the same doors — which is exactly the kind of portability the UK's own five-board system is designed to guarantee internally.