AP Calculus AB vs BC: Which Should You Take?
Quick answer: AP Calculus AB covers eight units of calculus, designed to match a first-semester college calculus course. AP Calculus BC covers those same eight units plus two more: parametric, polar and vector-valued functions (Unit 9) and infinite sequences and series (Unit 10), and is designed to match both first and second semester college calculus. Both exams have the same structure: 3 hours 10 minutes, 42 multiple-choice and 6 free-response questions, and both are on Monday, May 10, 2027. BC students also get a separate AB subscore, which colleges are advised to treat like an AB exam score.
What the two courses share
According to the College Board course overviews, AB and BC share Units 1 to 8 (AP Calculus AB overview; AP Calculus BC overview):
Unit 1: Limits and Continuity
Unit 2: Differentiation: Definition and Fundamental Properties
Unit 3: Differentiation: Composite, Implicit, and Inverse Functions
Unit 4: Contextual Applications of Differentiation
Unit 5: Analytical Applications of Differentiation
Unit 6: Integration and Accumulation of Change
Unit 7: Differential Equations
Unit 8: Applications of Integration
BC then adds:
Unit 9: Parametric Equations, Polar Coordinates, and Vector-Valued Functions
Unit 10: Infinite Sequences and Series
The BC overview also says the course "develops additional integration techniques and applications" beyond AB. So BC isn't a different subject. It's AB plus roughly a second semester of content, taught in the same school year.
The exam: identical structure
For May 2027, both exams follow the same format (College Board — AP Calculus AB exam):
Section I, Part A (multiple choice): 29 questions · 62 minutes · no calculator · 35% of the score
Section I, Part B (multiple choice): 13 questions · 38 minutes · graphing calculator required · 15%
Section II, Part A (free response): 2 questions · 30 minutes · graphing calculator required · 16.7%
Section II, Part B (free response): 4 questions · 60 minutes · no calculator · 33.3%
Two things stand out. First, more than two-thirds of the score comes from no-calculator sections, so by-hand algebra and calculus matter in both courses. Second, the exam is hybrid digital: multiple-choice questions are answered in the Bluebook app, and free-response answers are handwritten in paper booklets.
The College Board also notes that the multiple-choice count and timing were updated for May 2027, while "course content has not changed."
The AB subscore, explained
Every BC student receives two results: a BC score (1–5) and an AB subscore (1–5). The subscore reflects performance on "the part of the exam devoted to Calculus AB topics, which is approximately 60% of the exam" (College Board — BC score structure).
The College Board recommends that colleges treat the subscore "the same way they would treat an AP Calculus AB Exam score." Each college still sets its own credit policy.
What the 2025 numbers show. Across 160,953 students, the AB subscore distribution was (College Board — 2025 AB subscore distribution):
AB subscore 5: 47.7%
AB subscore 4: 30.5%
AB subscore 3: 9.8%
AB subscore 2: 9.0%
AB subscore 1: 3.0%
That's 88.0% at 3 or above. Bear in mind this group chose BC, so it tends to be strong in math. It's not a prediction for any one student.
Why it matters: a student who finds Units 9–10 hard can still come away with an AB-level result from the BC exam. That safety net is one reason some students choose BC.
A taste of each course
AB-level (shared) example
Find the derivative of y = sin(3x).
Chain rule: dy/dx = 3cos(3x).
Evaluate the integral of 3x² from 0 to 2.
The antiderivative is x³, so 2³ − 0³ = 8.
BC-only example
Find the sum of the infinite geometric series 1 + 1/2 + 1/4 + 1/8 + …
First term a = 1 and ratio r = 1/2. Since |r| < 1, the sum is a / (1 − r) = 1 / (1/2) = 2.
Series questions like this, plus convergence tests and Taylor polynomials, are central to Unit 10.
AB or BC: how to decide
Strong in algebra and precalculus, planning a STEM major: BC
Wants calculus but finds the pace of advanced math demanding: AB
Has a heavy senior-year schedule: AB, then decide on further math in college
Took AB already and wants more: check whether the school offers BC as a follow-on
Isn't sure precalculus is solid yet: strengthen precalculus first (AP Precalculus or an honors course)
This guide is MMS editorial advice. Course availability and prerequisites vary by school.
Common mistakes
Assuming BC is "AB but harder" everywhere. The shared units are tested at the same conceptual level. The difference is mostly extra content and pace.
Ignoring the no-calculator sections. They're worth more than two-thirds of the score.
Treating the AB subscore as automatic credit. It's a recommendation. Each college sets its policy.
Starting BC with weak trigonometry and algebra. Gaps show up fast in Units 2–3.
When extra support might help
Support is worth considering when precalculus gaps are slowing calculus, when the pace of BC feels overwhelming, or when a student wants structured free-response practice before May.
A tutor can't guarantee an AP score, but can strengthen the algebra and trig that calculus relies on and practice exam-style questions. Math Make Smart offers AP test preparation and online math tutoring, and you can book a free trial lesson. For the course before calculus, see our AP Precalculus exam guide; for how scores turn into credit, see AP scores explained.
Frequently asked questions
Is AP Calculus BC harder than AB?
BC covers more content (two extra units) at a faster pace. The shared topics are tested at the same level.
Do I need to take AB before BC?
Not always. Many schools let strong students go straight from precalculus to BC. Check your school's policy.
What is the AB subscore?
A separate 1–5 score for the AB portion of the BC exam, about 60% of it.
When is the 2027 AP Calculus exam?
Both AB and BC are on Monday, May 10, 2027.