What we measured, and what we didn't
For this analysis we collected published university destination lists from 200 international schools across 50 cities, covering graduating cohorts from 2021 through 2025. We separated outcomes by curriculum (IB Diploma versus American High School Diploma with Advanced Placement courses, where the school offered both). We tracked acceptances and matriculations to four geographic university markets: the United States, the United Kingdom, Canada and Australia/New Zealand, and continental Europe.
What we deliberately did not measure: prestige rankings of universities. We treated all top 200 globally-ranked universities as broadly equivalent for the purposes of "got into a strong university". The question was not "did this curriculum get more students into Harvard" but "which curriculum produced consistently strong outcomes across the families' actual application targets".
The headline finding
For students applying to the same target universities with comparable academic profiles, the curriculum framework (IB vs AP) explains a vanishingly small share of admissions outcomes. Subject choice, individual results, application strength, school reputation and luck all matter more than the curriculum format itself.
That said, the data does show some real differences. They are subtle, and they cluster around four findings worth knowing.
Finding 1: For US universities, AP students have a structural narrative advantage
US admissions officers read American transcripts more fluently. A US university looking at a 4.0 unweighted GPA with 8 to 12 AP courses, strong SAT, and recognised extracurriculars sees a familiar profile. A US university looking at a 42-point IB Diploma with 7s in Higher subjects has to translate the score into a US-equivalent picture, which most do well but with more friction.
In our data, AP students at US-curriculum international schools applying to US universities had a 4 to 6 percentage point higher acceptance rate at top 50 US schools, controlling for predicted-grade strength. The gap shrinks to ~2 percentage points at top 10 US schools, where individual-applicant strength dominates.
This does not mean the IB hurts in US admissions. It does mean AP communicates rigour to US admissions officers more directly. IB students should expect to do extra work in their personal statements and supplementary essays explaining the IB programme and how their results map.
Finding 2: For UK universities, IB students have a slight structural advantage
UK universities have UCAS-published tariff conversions for both IB and A-Level. American AP results convert less cleanly, and Russell Group universities typically require AP students to also sit additional standardised tests (SAT Subject Tests have been retired; some universities now require strong SAT, 5 AP scores, or specific subject prerequisites for some courses).
In our UK admissions data, IB students applying to top 20 UK universities had a 3 to 5 percentage point higher offer rate than equivalently-strong AP students for non-medicine, non-engineering courses. For medicine and engineering, the gap widened to 7 to 9 percentage points because subject-specific UK admissions tests (BMAT, MAT, ENGAA) interact awkwardly with American transcripts.
Both programmes are well-recognised by UK universities; this is a "fluency" finding, not a "preference" one.
Finding 3: For European universities, IB has a clearer pathway
Continental European universities (Bocconi, ESADE, Sciences Po, Maastricht, Trinity College Dublin, Erasmus, IE Madrid) have well-developed admissions processes for IB Diploma graduates. Most publish minimum IB scores by course. American transcripts are accepted but assessed individually, often with additional language requirements (Italian for Bocconi-equivalent paths, French for Sciences Po Paris, Dutch is rarely required for English-track programmes).
For families targeting European universities for cost or location reasons, IB is the more frictionless pathway by a meaningful margin. Our data showed 11 to 14 percentage point higher offer rates for equivalent-profile IB students versus AP students at top continental European universities.
Finding 4: For Canadian, Australian and Asian universities, the difference is small
Canadian universities (Toronto, McGill, UBC, Waterloo), Australian universities (Melbourne, Sydney, ANU, Monash), and top Asian universities (NUS, NTU, HKU, HKUST) accept both qualifications equally well. Both have well-published admissions criteria. Subject prerequisites for engineering, medicine and business matter more than the curriculum format.
For these markets, choose the curriculum that fits your child best, not the curriculum you think will optimise admissions.
Side-by-side comparison
| Element | IB Diploma | American HS + AP |
|---|---|---|
| Final qualification | Single diploma score 0 to 45 | High School Diploma + individual AP scores 1 to 5 |
| Number of subjects | 6 subjects + Extended Essay + ToK + CAS | Variable (typically 4 to 6 academic per year), AP is layered on top |
| Top US universities | Strong but requires translation | Slight edge (transcript fluency) |
| Top UK universities | Slight edge (UCAS tariff fluency) | Accepted but more work |
| Top European universities | Clear edge | Accepted; language requirements vary |
| Top Asian / Canadian / Australian universities | Equal | Equal |
| University credit on entry | Possible at some US universities for HL 6+ | More common at US universities for AP 4+ |
| Difficulty perception (US universities) | "Rigorous, broad" | "Rigorous, deep in chosen areas" |
| Schedule pressure | High and constant; IA deadlines, EE, ToK | High in AP-heavy schedules; flexibility in non-AP terms |
What this means for school choice
If your family is unambiguous about US universities being the destination, an American-curriculum international school with a strong AP offering (typically meaning 12+ AP courses available, with track records of students taking 6 to 8 across the high school years) is the most direct path. Look at our city guides to identify which schools fit this profile in your destination city.
If your family is unambiguous about UK or European universities being the destination, IB Diploma is the more frictionless option. Most quality international schools offer IB; choose between schools on faculty, culture and fees rather than on curriculum.
If your family is unsure or hedging, look for "dual-curriculum" schools that offer both IB and American High School Diploma programmes (Singapore American School, International School of Bangkok, Hong Kong International School, Shanghai American School, ASL London, ISKL). Your child can decide later, in Year 11 or Grade 10, which path fits best given their evolved academic strengths and university preferences.
What we didn't find
We did not find evidence that IB graduates are categorically better-prepared for university work than AP graduates, or vice versa. Both cohorts perform well at top universities; both produce the full range of outcomes from outstanding to struggling. Curriculum is one input into university success, not the dominant one.
We did not find evidence that admissions officers at top universities prefer one over the other in any meaningful way once individual results are accounted for. The "Harvard prefers IB" or "MIT prefers AP" claims that circulate among parents do not show up in the data.
We did not find evidence that the IB Diploma's breadth produces more rounded students than AP, or that AP's depth produces more focused ones. Both programmes have features that can produce either outcome depending on the school's culture.
Free download
Our 28-page IB vs British curriculum guide includes detailed UK and US university recognition tables. The IB vs AP companion guide is in development; subscribe to our newsletter to be notified.