The MCAT Sections: What Is the Structure of the MCAT Exam?

Table of Contents

The MCAT test day can span over 8 hours, so it’s good to know what to expect. The actual seated time is approximately 7.5 hours, while the testing lasts about 6.25 hours. The structure of the exam is fairly simple. The MCAT is split into four sections or subtests, each lasting 90 or 95 minutes. You’ll notice that the name of each Science section includes “Biological” to illustrate the across-the-board emphasis on testing concepts in a biological context.

Breakdown of the MCAT Sections

SectionsTime Allotted# of Passages# of Questions% of Subjects
Chemical and Physical Foundations of Biological Systems
(Physical Sciences)
95 minutes10 passages59 multiple-choice questions
44 passage-based
15 freestanding
General Chemistry (30%)
Biochemistry (25%)
Physics (25%)
Organic Chemistry (15%)
Biology (5%)
Critical Analysis and
Reasoning Skills
(CARS)
90 minutes9 passages53 multiple-choice questions
53 passage-based
0 freestanding
Passages cover topics in Social Sciences and Humanities but no prior knowledge is expected.
Biological and Biochemical Foundations of Living Systems (Biological Sciences)95 minutes10 passages59 multiple-choice questions
44 passage-based
15 freestanding
Biology (65%)
Biochemistry (25%)
General Chemistry (5%)
Organic Chemistry (5%)
Psychological, Social, and Biological Foundations of Behavior (Behavioral Sciences)95 minutes10 passages59 multiple-choice questions
44 passage-based
15 freestanding
Psychology (65%)
Sociology (30%)
Biology (5%)

What is the most important MCAT section?

The CARS section is the most important section both as a percentage of your MCAT scores and in terms of its significance in the admissions process.

The CARS section accounts for 25% of your total score. That’s more than Biology (20%), Psychology (16%), Biochemistry (12%), Chemistry (9%), Sociology (7%), Physics (6%), and Organic Chemistry (5%).

Many medical school admissions committees regard your CARS score as the most important section score because it exemplifies your ability to think critically. A few medical schools now only look at your CARS score. Others have stricter cutoffs for CARS than for the Science sections. Medical schools are looking for the intellectual dexterity that is embodied in your CARS score.

Free MCAT Consultation

Do you have any questions about your MCAT goals? Prep101 is here to help you every step of your MCAT journey. Use our scheduling app to book a free 20-minute consultation with one of our expert coaches. These MCAT specialists have guided thousands of students from different backgrounds and circumstances to accomplish their MCAT goals — and they can help you too.

About the Author

Isabella R. is the Head MCAT Coach at Prep101, where she leads a team of expert coaches committed to helping students achieve their highest possible scores. With years of experience in MCAT prep and a passion for both medicine and mentorship, Isabella has helped hundreds of students navigate the complexities of the exam. She specializes in customizing MCAT prep to fit each student’s unique needs, and loves sharing the strategies and insights that helped her achieve a 517 on the MCAT. When she’s not coaching, you can find Isabella staying on top of the latest MCAT trends to ensure Prep101’s students always have the most effective tools at their fingertips.
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