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How IB grade boundaries work: who sets them and why they move

By Michael Thompson - Head of Teaching Excellence; 15 years as an IB Coordinator

Published 5 October 2026Data: IB Diploma Programme provisional statistical bulletin, May 2026

Short answer: The IB sets grade boundaries after marking, separately for each subject, level and session, so they change from year to year and are not published in advance.

Grade boundaries are the marks that separate one IB grade from the next, and they cause a lot of confusion. Students often want a fixed number to aim for, but the system does not work that way.

This explainer covers who sets the boundaries, why they change from session to session, and what you can realistically use instead. The headline figures come from the IB's official provisional statistical bulletin for May 2026: a mean points score of 30.9 and a pass rate of 82.6%.

Key figures

30.9

Mean total points

82.6%

Diploma pass rate

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Who sets the boundaries

The IB sets grade boundaries, and it does so after the exam scripts have been marked, not before. Teachers, schools and tutors do not set them. A boundary is the minimum total mark in a subject needed for a given grade from 1 to 7, so it can only be fixed once the marks for that session exist.

Why boundaries move between sessions

Because boundaries are decided after marking, they are not a permanent scale. Two sessions can use different papers, and a paper can turn out slightly harder or easier than the one before. Setting boundaries afterwards allows the mark needed for a grade to reflect the paper actually sat. For you, the practical lesson is that a mark that earned a particular grade in one session is not a guarantee of the same grade in another. Treat past boundaries as a rough guide only.

Who gets to see them

Per-subject boundaries are released to the IB coordinators at schools rather than published openly. The bulletin gives no reasons for this, so we do not speculate about it. In practice, if you want to know about boundaries, your school's IB coordinator is the person to ask. Be wary of unofficial tables online that claim to show exact boundaries for a subject.

Using grade distributions to judge a subject

Grade distributions, by contrast, are published. A distribution shows what share of candidates reached each grade from 1 to 7 in a subject. Look at where most candidates sit, how many reach 6 and 7, and how many fall at the bottom. Compare several sessions rather than one, because a single session can be unusual. Distributions describe outcomes after the boundaries were applied, so they show how candidates have actually fared in a subject, although they also reflect who chooses it.

Putting the May 2026 headline figures in context

The May 2026 mean points score of 30.9 and pass rate of 82.6% describe diploma candidates with a result as a group. They are useful background, but they say nothing about any individual subject or about where a particular boundary fell. For subject-level decisions, go to the subject's grade distribution.

Key takeaways

  • The IB sets grade boundaries after marking, so they are not fixed in advance.
  • Boundaries can move between sessions, so past boundaries are only a rough guide.
  • Per-subject boundaries are released to schools' IB coordinators rather than published openly.
  • Published grade distributions are the best public evidence for judging a subject.
  • In May 2026 the mean points score was 30.9 and the pass rate was 82.6%.

Frequently asked questions

Who decides IB grade boundaries?
The IB decides them, after the exam scripts have been marked. Because they are set once the marks are known, they are not announced before the session.
Are IB grade boundaries the same every session?
No. They can move between sessions because they are set after marking and the papers differ. Use earlier boundaries as a rough guide, not as a promise.
Where can I find grade information for a subject?
Per-subject boundaries go to schools' IB coordinators rather than being published openly, so ask your coordinator. Grade distributions are published and show how candidates were spread across grades 1 to 7.

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Sources