If you are choosing between the USA Biology Olympiad (USABO) and the British Biology Olympiad (BBO), the most useful thing to know is that you usually do not have to choose. The two exams overlap by roughly 90% of their content, and from 2026 the BBO sits in January while the USABO China-region Open Exam falls in early April — so a single, well-planned preparation cycle can target both, with the BBO acting as a low-stakes warm-up for the USABO. This page lays out how the two compare and how to sequence them.
Why one prep cycle covers both
USABO and BBO are written for the same kind of student and test largely the same biology. The shared core spans cell biology, genetics and evolution, animal and plant anatomy and physiology, and ecology. Because the content overlap is so high, the marginal cost of adding the second exam to your plan is small — you are mostly re-using the same knowledge under a different paper format.
The sequencing matters. Sitting the BBO first gives you a real, timed exam in January — exam-room experience, a score to calibrate against, and a clear list of weak topics — all roughly ten weeks before the USABO. You then spend those ten weeks closing the gaps the BBO exposed, rather than walking into the USABO cold.
How the two papers differ
The biology is shared; the format is not. Knowing the difference tells you how to practise for each:
| USABO (Open Exam) | BBO | |
|---|---|---|
| Organiser | Center for Excellence in Education (CEE), USA | Royal Society of Biology, UK |
| 2026 timing | Late March | January (registration early Jan, exam mid-Jan) |
| Format | 50 minutes, 50 multiple-choice questions, no penalty for wrong answers | 90 minutes, written: multiple-choice, fill-in and ordering questions, no lab |
| Best practised by | Speed and accurate recall under time | Precise written answers and ordering logic |
Both reward the same underlying mastery, so the smartest plan is to build the biology once and then drill each paper's format in the weeks before it. For the question style itself, work from real past papers — see our USABO past-papers hub for how to use them.
Going for the “double gold”
Because the content overlap is so high, a strong, well-prepared student can realistically target medals in both exams from a single preparation cycle. This is not theoretical. In the 2026 season, Hanlin's biology cohort earned 26 BBO golds, 21 silvers and 5 bronzes, and five students reached the USABO US-region Semifinal (per Hanlin's own records). The pattern behind those results is exactly the one above: build the shared core, use the January BBO as a graded checkpoint, then convert that into a sharper USABO run in March.
The biology faculty behind that approach are subject specialists — for example, one of our biology tutors holds a biology honours degree from the University of Toronto and a master's in plant biotechnology from Wageningen University, and teaches the USABO/BBO sequence as a single integrated course. Whether you self-study or work with a tutor, the principle is the same: prepare the biology once, sit the papers in order.
Frequently asked questions
Should I sit BBO or USABO first?
For 2026, sit the BBO first. It falls in January, about ten weeks before the USABO China-region Open Exam in early April, so it works as a graded warm-up that shows you exactly what to fix before USABO.
How much do USABO and BBO actually overlap?
Roughly 70-90% (our own syllabus comparison) of the content — cell biology, genetics and evolution, animal and plant anatomy and physiology, and ecology. The main differences are paper format and length, not the biology.
Can I really medal in both from one prep cycle?
Strong students do. The high content overlap means one study plan serves both papers; you then drill each paper's format in the weeks before it. Results vary by student — confirm current rules and dates on the official channels.
Is USABO harder than BBO?
They test similar biology at a similar level. USABO's Open Exam is a fast 50-question multiple-choice paper; BBO is a longer written paper. “Harder” depends on which format suits you — another reason to sit both.
This is an independent English-language guide for students preparing for the USA Biology Olympiad, operated by Hanlin Education. It is not affiliated with, endorsed by, or sponsored by the Center for Excellence in Education or the Royal Society of Biology. Cohort results are per Hanlin's own records and vary by student. Dates, formats and eligibility can change each year — confirm current details through the official USABO and BBO channels.