IB grade boundaries are the specific raw score ranges that determine which final grade (1 through 7) you receive in each subject — and understanding how they’re actually set removes a lot of confusion around why the “same” percentage can produce a different grade from one exam session to the next.
What a Grade Boundary Actually Is
For each subject, the IB publishes a table showing which range of raw marks (the actual points scored across your exam papers and any internally assessed components) corresponds to each grade from 1 to 7. For example, a hypothetical boundary table might show that 65-100% of the total available marks earns a 7, while 55-64% earns a 6, and so on down to grade 1. These exact ranges are published separately for every subject, every level (HL/SL), and every exam session.
Why Boundaries Aren’t Fixed at the Same Percentage Every Year
Unlike a school test where 90% might always mean an A, IB grade boundaries are not fixed in advance — they’re determined after each exam session based on the overall difficulty and performance data from that specific set of papers. This process, called grade awarding, involves senior examiners reviewing statistical data and actual student responses to ensure a grade 7 in a harder exam session represents the same standard of achievement as a grade 7 in an easier one.
How the Grade Awarding Process Works
After each exam session, IB examiners and senior subject specialists review a combination of statistical evidence (how the overall cohort performed) and qualitative evidence (looking at actual scripts at proposed boundary points) to set boundaries that reflect consistent standards year over year — the goal is that a grade 6 always represents a comparable level of genuine subject mastery, even if the specific exam questions varied in difficulty.
Why This Matters for How You Should Interpret a Mock Exam
Because your school sets its own boundaries for internal mock exams (often using boundaries from a previous real exam session, since the actual boundaries for your specific exam haven’t been set yet), your mock result is a useful estimate, not a guaranteed preview of your final grade — the real boundaries for your actual exam session could end up slightly higher or lower depending on that session’s overall difficulty and cohort performance.
Do Grade Boundaries Vary Significantly Between Subjects?
Yes, meaningfully. A subject with a historically demanding exam style might have a grade 7 boundary requiring a lower raw percentage than a subject where achieving top marks is comparatively more straightforward — this doesn’t mean one subject is “easier to pass” in an absolute sense, but it does mean you can’t directly compare raw percentage scores across different subjects (see our companion guide on grade boundary trends by subject).
How to Find the Actual Grade Boundaries for Your Session
Official grade boundaries are released to schools by the IB shortly after each results day (early July for the May session, and in January for the November session) — your IB coordinator has access to these, and they’re generally not published in a way easily accessible directly to students beforehand, since they’re finalized only after the exam awarding process concludes.
Common Misunderstandings About Grade Boundaries
- Assuming a fixed percentage (like “70% always equals a 6”) applies across all subjects and sessions — it doesn’t
- Treating a mock exam boundary as identical to what your real exam boundary will be
- Assuming grade boundaries “punish” a harder exam session — the awarding process is specifically designed to prevent this, adjusting boundaries to maintain consistent standards
Final Tip
Rather than fixating on a specific percentage target, focus your revision on genuinely mastering the subject content and command terms used in your specific subject’s assessment criteria — grade boundaries are designed to reward that underlying mastery consistently, regardless of exactly where the raw percentage cutoff lands in any given session.