IB Diploma SL Biology SL Grade Boundaries

IB Biology SL combines Paper 1 (multiple choice + data), Paper 2 (structured/extended response), and the Internal Assessment (24 marks). Your raw mark is the sum across all three components. The IB Coordinator portal at your school is the authoritative source for your component marks; the figures shown here reflect typical published session boundaries.

Yes — your raw mark is the sum of your marks from all papers in the subject. For example, if Biology SL has two papers and you scored 65/100 on Paper 1 and 72/100 on Paper 2, your total raw mark is 137/200. Enter 137 in the tool to see your grade.

The Internal Assessment (or, for Economics, the IA portfolio of commentaries) typically contributes 20% of the final mark in IB Biology SL (30% at SL Economics). Your raw mark on the tool should be the combined total across written papers and the IA. The IA is moderated, not externally examined — your teacher's mark may be adjusted up or down by IB moderators.

This tool has grade boundary data for the following years: 2024, 2023, 2022. All data is from the May/June examination series, which is the main series for most students.

Grade boundaries are adjusted each year so that students who performed as well as an average student from a previous year receive the same grade, regardless of whether that year's paper was harder or easier. This process is called grade protection (Cambridge) or comparable outcomes (Ofqual). A harder paper will have lower boundaries; an easier paper will have higher ones.

If your mark is within 2–3 marks of the next grade boundary, it may be worth asking your school about an Enquiry About Results (EAR) or a clerical check. One mark can sometimes be the difference between grades. Note that mark reviews can result in grades going up, staying the same, or going down — discuss with your teacher before requesting one.

These boundaries reflect typical patterns from published IB Subject Reports across recent May sessions. The IB does not publish a single public boundary PDF — definitive thresholds are released to schools through the IB Coordinator portal after each session. Treat these figures as a reference band; your IB Coordinator has the official numbers.

The terms are used interchangeably. A grade threshold (Cambridge terminology) or grade boundary (AQA/Edexcel terminology) is the minimum raw mark needed to achieve a particular grade in that examination series.