IB grade boundaries: how they're set, why they change, and why one paper can't predict your 7

IB grade boundaries are the mark ranges that turn your total marks in a subject into a grade from 7 down to 1 (or A to E for TOK and the Extended Essay). They aren't fixed in advance: they're set after each exam session, at a stage the IB calls grade awarding, by senior examiners and IB staff who look at how the papers actually worked. That's why boundaries differ from one session to the next and between the time-zone versions of a paper, and why the IB gives them to schools after results rather than to students beforehand.

This guide explains how that process works and what it means for you. It deliberately doesn't print boundary numbers: they belong to a single session and paper, and they mislead more often than they help when copied onto a new one.

What exactly is a grade boundary?

Most IB subjects have several components: two or three exam papers plus an internal assessment (IA). Each component is marked out of its own total, and each has its own boundaries for that session. The subject boundaries are then built from the component ones. Your marks from every component are combined according to the subject's weightings into one total, and that total is converted into your 1–7.

So there are really two kinds of boundary:

• Component boundaries: the marks needed for each grade on one paper or the IA in one session.
• Subject boundaries: the weighted totals needed for each grade overall. These decide the grade on your results.

Your IA mark joins that total only after moderation. Your teacher marks the IA, the IB re-marks a sample of your teacher's class, and all of that teacher's marks can then be adjusted up or down. The IA mark you were told in school isn't necessarily the mark that counts.

How are IB grade boundaries set?

Marks become grades shortly before results are released. For each subject, senior examiners and IB staff meet and agree the boundaries. According to the IB's own description of the process, they draw on:

• examiners' judgement of the work candidates actually produced;
• statistical evidence about how the papers performed;
• the grade descriptors, which describe in words what work at each grade looks like;
• feedback from teachers on how the papers went.

The idea is that a 6 should reflect a similar standard of work whichever session you sat. If a paper turned out harder than intended, the boundaries for it can go down; if it was easier, they can go up. That's fairer than a fixed percentage: you aren't punished for sitting a tough paper.

TOK and the Extended Essay work the same way with letter grades. For the new Extended Essay, marked out of 30 from May 2027, the IB's guide says boundaries can change between sessions while the grade descriptors stay fixed. No boundaries exist yet for that 30-mark scale; the first will be set after the May 2027 session.

Why do grade boundaries change between sessions and time zones?

Every session has new papers, and no two papers are exactly equally hard. Boundaries move to absorb that difference, so a change in a boundary usually tells you about the paper rather than about the students.

Within one session there can also be more than one version of a paper. The IB sets papers in variants for different time zones, so that questions can't leak from one region to another. (Older past papers are labelled TZ0, TZ1 or TZ2; newer exam schedules talk about exam zones.) Different questions mean different difficulty, so each variant can have its own boundaries, even though it's the same subject, the same level and the same week.

A new course adds one more source of movement. Biology and Chemistry were first examined on their current courses in 2025, ESS and Global Politics in 2026, and Psychology will be in 2027. For the first sessions of a new course there are few earlier sessions on the same papers to compare against, which is one more reason not to lean on boundaries from the old course when you mark a new-format paper.

Can you predict a 7 from a past paper and a grade boundary?

Not reliably. It's tempting to sit a past paper, mark it, look up that session's boundary and conclude "that's a 7". Five things get in the way:

1. It's one component, not the subject. Your grade comes from the weighted total of all your components. A strong Paper 2 can be pulled down by a weaker Paper 1 or IA.
2. It's one session's boundary. The boundary for your own session will be set on your papers, after you've sat them. It may be higher or lower.
3. Your self-marking is probably kinder than an examiner. Crediting what you meant rather than what you wrote is easy to do and adds marks that wouldn't exist in the real exam. The mark schemes guide covers how to mark strictly.
4. Your IA mark isn't final until it's moderated.
5. Conditions matter. A paper done with notes nearby, or without the clock running, isn't the same test.

To see how weightings work, take a simplified Biology example. The papers and IA are weighted 36%, 44% and 20%. A student scoring 70% on Paper 1, 85% on Paper 2 and 60% on the IA has a weighted total of 0.36 × 70 + 0.44 × 85 + 0.20 × 60 = 25.2 + 37.4 + 12.0 = 74.6%. The excellent Paper 2 is diluted by the other two components: Paper 1 and the IA pull the total down by about the same amount. The real conversion is done on marks, not percentages, but the principle holds: every component counts in proportion to its weight.

Where can you find IB grade boundaries?

After each session the IB sends the boundary documents to schools, and your IB coordinator can access them. Asking your subject teacher is usually the quickest route, since teachers use them for marking mocks. We haven't found a public page on ibo.org that lists them.

Various websites collect boundary tables from past sessions. If you use one, check three things before trusting a number: the session (May or November, and which year), the time-zone variant, and whether it refers to the current course. A boundary for an old-syllabus Biology paper with a Paper 3 tells you nothing about the current two-paper exam. Your teacher can tell you whether a table matches the paper you just sat.

What do grade boundaries mean for your revision?

Very little day to day, and that's the useful part. You can't influence a boundary; you can only increase your marks. In practice:

• Track marks, not grades. Record your percentage per paper and per topic over time. A rising line across several papers is good evidence; one high score isn't.
• Treat the IA as banked marks. It's worth at least 20% in Biology, Chemistry, Maths, ESS, Psychology and Global Politics, and you finish it before the exam. Marks gained there count whatever happens to the paper boundaries in May.
• Chase the marks that are cheapest to fix. Command-term mistakes, missing units, vague wording and unanswered questions cost marks on every paper, in every session. They're easier to fix than a whole topic.
• Don't relax because "the boundary for a 7 was low last year". If the paper was hard for everyone, it was hard for you too. Low boundaries usually mean a hard paper, not an easy grade.

Boundaries also feed into your Diploma total. How subject grades, TOK and the Extended Essay add up to 45, and which combinations fail the Diploma, is covered in how the IB is scored. For the grade your school sends to universities before results, see the guide to predicted grades. And when you're ready to start marking practice papers, where to get past papers legally covers which ones match your syllabus.