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IB Diploma Programme · Standard Level · Every session on record

IB Biology SL Grade Boundaries

Every official grade boundary on record for Biology at Standard Level — overall and component by component, straight from the IB's own grade boundary documents.

11 sessions 2021–2026 Grade 7: 74%–81% Free · no signup

Compiled by Evangelos Kotronis, active IB examiner · Updated 22 August 2026

Quick answer

In the most recent session on record (May 2026 TZ3), IB Biology SL students needed 75/100 overall for a Grade 7, 61/100 for a Grade 6, and 35/100 for a Grade 4. Across all 11 sessions listed here the Grade 7 threshold has ranged from 74% to 81%.

IB Biology SL grade boundaries by session

Mark ranges are inclusive — “42–54” means 42, 43 … 54 all earn that grade. Overall is the composite total out of 100 scaled marks. The percentage beneath each range is of that component's own maximum for that session, because paper totals shift slightly from one session to the next.

May 2026 TZ3 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1213–2213%+23–3423%+35–4735%+48–6048%+61–7461%+75–10075%+
Paper 1 (MCQ)0–78–1026.7%+11–1236.7%+13–1543.3%+16–1953.3%+20–2266.7%+23–3076.7%+
Paper Two0–45–910%+10–1420%+15–2230%+23–2946%+30–3760%+38–5076%+
Paper 1 B0–23–412%+5–820%+9–1136%+12–1448%+15–1760%+18–2572%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

May 2026 TZ2 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1314–2314%+24–3524%+36–4736%+48–6048%+61–7361%+74–10074%+
Paper 1 (MCQ)0–78–1026.7%+11–1236.7%+13–1543.3%+16–1953.3%+20–2266.7%+23–3076.7%+
Paper Two0–56–1012%+11–1622%+17–2334%+24–2948%+30–3660%+37–5074%+
Paper 1 B0–23–412%+5–720%+8–1032%+11–1444%+15–1760%+18–2572%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

May 2026 TZ1 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1314–2514%+26–3726%+38–5038%+51–6351%+64–7664%+77–10077%+
Paper 1 (MCQ)0–78–1126.7%+12–1340%+14–1646.7%+17–1856.7%+19–2163.3%+22–3073.3%+
Paper Two0–56–1112%+12–1824%+19–2538%+26–3352%+34–4068%+41–5082%+
Paper 1 B0–23–412%+5–720%+8–1032%+11–1444%+15–1760%+18–2572%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

November 2025 TZ3 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1314–2314%+24–3824%+39–5139%+52–6352%+64–7664%+77–10077%+
Paper 1 (MCQ)0–78–926.7%+10–1233.3%+13–1743.3%+18–2160%+22–2673.3%+27–3090%+
Paper Two0–56–1012%+11–1822%+19–2438%+25–3050%+31–3662%+37–5074%+
Paper 1 B0–23–512%+6–924%+10–1240%+13–1552%+16–1864%+19–2576%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

November 2025 TZ1 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1314–2414%+25–3925%+40–5140%+52–6552%+66–7766%+78–10078%+
Paper 1 (MCQ)0–78–1026.7%+11–1536.7%+16–1953.3%+20–2366.7%+24–2780%+28–3093.3%+
Paper Two0–56–1012%+11–1722%+18–2336%+24–3048%+31–3662%+37–5074%+
Paper 1 B0–23–512%+6–924%+10–1240%+13–1552%+16–1864%+19–2576%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

November 2024 TZ2 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1516–2816%+29–4229%+43–5443%+55–6755%+68–8068%+81–10081%+
Paper 1 (MCQ)0–78–1026.7%+11–1436.7%+15–1850%+19–2363.3%+24–2780%+28–3093.3%+
Paper Two0–78–1416%+15–2130%+22–2744%+28–3256%+33–3866%+39–5078%+
Paper Three0–45–814.7%+9–1326.5%+14–1741.2%+18–2252.9%+23–2667.6%+27–3479.4%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

November 2024 TZ1 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1314–2514%+26–3926%+40–5140%+52–6352%+64–7564%+76–10076%+
Paper 1 (MCQ)0–78–1026.7%+11–1236.7%+13–1643.3%+17–1956.7%+20–2366.7%+24–3080%+
Paper Two0–56–1112%+12–1924%+20–2540%+26–3252%+33–3866%+39–5078%+
Paper Three0–45–814.3%+9–1325.7%+14–1740%+18–2051.4%+21–2460%+25–3571.4%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

November 2023 TZ2 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1415–2615%+27–4027%+41–5341%+54–6554%+66–7866%+79–10079%+
Paper 1 (MCQ)0–78–927.6%+10–1234.5%+13–1744.8%+18–2262.1%+23–2779.3%+28–2996.6%+
Paper Two0–67–1314%+14–2028%+21–2642%+27–3154%+32–3764%+38–5076%+
Paper Three0–45–814.3%+9–1325.7%+14–1740%+18–2151.4%+22–2562.9%+26–3574.3%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

November 2023 TZ1 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1415–2615%+27–3827%+39–5139%+52–6452%+65–7765%+78–10078%+
Paper 1 (MCQ)0–78–926.7%+10–1133.3%+12–1640%+17–2156.7%+22–2673.3%+27–3090%+
Paper Two0–78–1416%+15–2030%+21–2642%+27–3254%+33–3866%+39–5078%+
Paper Three0–34–711.4%+8–1122.9%+12–1534.3%+16–2045.7%+21–2460%+25–3571.4%+
Practical Work0–34–616.7%+7–1029.2%+11–1345.8%+14–1658.3%+17–1970.8%+20–2483.3%+

November 2022 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1415–2515%+26–3826%+39–5039%+51–6451%+65–7765%+78–10078%+

November 2021 — IB Biology SL

ComponentGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7
Overall0–1314–2214%+23–3423%+35–4635%+47–6247%+63–7663%+77–10077%+

Source: official IB Diploma Programme grade boundary documents and subject reports.

Is the Grade 7 boundary rising?

Averaged across the record, the Grade 7 threshold in the later sessions sits about 1.4 percentage points lower than in the earlier ones — recent papers have been graded slightly more generously in raw-mark terms, most likely because they ran harder.

Overall Grade 7 threshold (% of 100 scaled marks) — November 2021 to May 2026 TZ3

68%84%100%November 2021: 77%77November 2021November 2022: 78%78November 2022November 2023 TZ1: 78%78November 2023 TZ1November 2023 TZ2: 79%79November 2023 TZ2November 2024 TZ1: 76%76November 2024 TZ1November 2024 TZ2: 81%81November 2024 TZ2November 2025 TZ1: 78%78November 2025 TZ1November 2025 TZ3: 77%77November 2025 TZ3May 2026 TZ1: 77%77May 2026 TZ1May 2026 TZ2: 74%74May 2026 TZ2May 2026 TZ3: 75%75May 2026 TZ3

How to read these boundaries

Grade boundaries are not fixed targets. The IB resets them after every session so that each grade represents the same standard of work, whether that session's paper ran hard or easy. That is why the mark needed for a 7 in IB Biology SL can move by several points from one session to the next while the syllabus stays identical.

For revision, use them as a calibration tool: sit a past paper under timed conditions, mark it against the official markscheme, then check what that total would have earned in the session that paper is from — not the most recent one. Comparing your marks component by component, rather than only the overall total, is what tells you where the marks are actually going.

The 6-to-7 gap is small

Across these sessions the distance between a 6 and a 7 has averaged just 13 marks out of 100 (narrowest 12, widest 14). On a paper marked out of 100 scaled marks, that is a handful of well-argued sentences.

Use the right session

The Grade 7 boundary here has swung 7 percentage points between May 2026 TZ2 (74%) and November 2024 TZ2 (81%). Marking a past paper against the wrong session's boundaries can mislead you by a whole grade.

Components move independently

The overall boundary is a composite. Individual papers are graded on their own scales and can be far more or less forgiving than the overall figure suggests, which is why every component is listed separately in the tables above.

Frequently asked questions

What percentage do you need for a 7 in IB Biology SL?

Across the 11 sessions on record, the overall Grade 7 boundary for IB Biology SL has ranged from 74% (May 2026 TZ2) to 81% (November 2024 TZ2) of the 100 available scaled marks. In the most recent session on this page, May 2026 TZ3, it was 75%. There is no fixed percentage: the IB resets the boundary after every session so that a 7 represents the same standard of work regardless of how hard that particular paper turned out to be.

How many marks separate a 6 from a 7 in IB Biology SL?

On the overall 100-mark scale, the gap between the Grade 6 and Grade 7 boundaries has averaged 13 marks, ranging from 12 to 14 marks. In May 2026 TZ3 a 7 started at 75 and a 6 at 61 — a 14-mark gap. That is a much smaller distance than most students assume, and it is usually closed with exam technique rather than extra content.

Do IB grade boundaries change every year?

Yes. They are set after each examination session by the IB's grade award process, once senior examiners have seen how candidates actually performed on that specific paper. For IB Biology SL the overall Grade 7 threshold has moved by 7 percentage points between its lowest and highest session on record. This is why you should always compare a past paper score against the boundaries from the session that paper is from, not the most recent session.

Why are there different timezones (TZ1, TZ2, TZ3) for IB Biology SL?

Candidates in different parts of the world sit different versions of the same examination so that papers cannot be leaked across time zones. Each version is graded separately with its own boundaries, which is why you will see TZ1, TZ2 and TZ3 listed with slightly different thresholds for the same month. Always use the boundaries for the timezone your paper was actually sat in.

Related grade boundaries

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