IB Chemistry Grade Boundaries: What's a Good Score?

Illustrative SL Chemistry boundaries (based on recent May sessions, out of 100 weighted marks):

These numbers shift a few points each session — check your actual results slip or ask your school for the session-specific boundaries, since the IB doesn't publish them until after results are released.

According to the IB's current Chemistry guide (first exams 2025), the weighting is: Paper 1 (multiple-choice and data-based questions) 36%, Paper 2 (short and extended response) 44%, and the Internal Assessment 20% — identical at SL and HL.

Worked example: A student scores 70% on Paper 1, 65% on Paper 2, and 80% on the IA.

Weighted total = (0.36 × 70) + (0.44 × 65) + (0.20 × 80) = 25.2 + 28.6 + 16.0 = 69.8%

That lands squarely in the typical grade 6 range.

Quick tip: don't chase the raw percentage — chase the skill gaps. A student stuck at grade 5 is almost always losing marks on Paper 2's extended-response questions (application and evaluation, not recall), not on basic content.

HL students sit longer papers (Paper 1 runs 2 hours at HL versus 1 hour 30 at SL) and cover additional higher-level topics like the sub-mechanisms of organic chemistry and advanced equilibrium calculations — so comparing raw scores between the two levels directly isn't meaningful.

This is called grade equating, and it's standard practice across large-scale assessment bodies, not something unique to the IB. It's why comparing your mock boundary directly to last May's published boundary can be misleading — the papers aren't identical in difficulty.

3 things to check before your next mock:

1. Are you losing marks on command terms — writing 'describe' when the question says 'explain' or 'evaluate'?
2. Is your IA scoring below 20/24 on any single criterion (especially Personal Engagement or Analysis)?
3. Are you consistently running out of time on Paper 2's longer six-mark questions?

In my years marking Paper 2 scripts, the single most common lost mark is students stating a conclusion without linking it back to the actual data given in the question — examiners award marks for the reasoning chain, not just the right final answer.

The IA is marked against five criteria in the current guide: Research Design, Data Collection and Processing, Conclusion, Evaluation, and Communication — each out of a set mark range totalling 24. Common mistake: students write a beautiful method but a thin Evaluation section, which costs marks even when the data itself is solid.

Steps that actually move the needle:

1. Do a full past paper under strict time limits, then mark it yourself against the official mark scheme — not just check the final answer.
2. Log every lost mark by topic, not by paper, so you can see the real pattern.
3. Rework your weakest topic using Revision Notes and a Topical Worksheet on RevisionPrep before attempting a fresh paper.
4. Repeat every two to three weeks, tracking whether your weighted percentage is climbing.

According to the IB's current Chemistry guide (first teaching 2023, first exams 2025), the syllabus is organised into structural, physical, and reactivity strands rather than the old numbered topic list — so past papers before 2025 use different topic labels and shouldn't be treated as a direct match for current content.

Check the specific offer, though — some competitive medicine programmes and highly selective engineering courses do specify a 7 in HL science subjects as a conditional requirement, so it's worth confirming against the actual university prospectus rather than assuming a 6 is always sufficient.

Quick tip for parents: if your child is unsure about their degree path in Year 11, choosing HL keeps more university doors open — it's far easier to have a strong HL grade and not need it than to need HL and only have taken SL.

On RevisionPrep, the Chemistry Revision Notes are organised by the current syllabus strands, the Topical Worksheets isolate exactly the weak areas a student's mock analysis reveals, and the Mock Papers replicate real timing conditions — the combination that tends to move students up a grade boundary rather than sideways within one.