Which MCAT^® Formulas Are Worth Memorizing?

I went looking for the official list of formulas you need for the MCAT^®. It does not exist.

The AAMC gives you a periodic table in the Chem/Phys section and nothing else. No equation sheet. No constants. No calculator. On that point, everyone agrees.

Past that, the advice splits. In one Student Doctor Network thread, a poster says to memorize every equation on the Kaplan quicksheets. The very next reply calls third-party formula sheets a placebo and the time spent on them wasted. MedLife Mastery publishes a tool listing about 190 equations worth knowing. Another prep site argues the exam will usually hand you the equation you need.

So the answer lies somewhere between zero and 190. Very helpful.

What the Outline Quietly Says

A tutor in that same SDN thread pointed somewhere more useful: the AAMC's own content outline. So I read it.

The Chem/Phys outline is the same topic list the AAMC hands its question writers, and it is mostly nouns. Scattered through those nouns, though, are equations written out in full. By my count there are 18 of them.

That is the closest thing to an official must-know list anyone will give you. The outline also names plenty more without writing them out: Poiseuille flow, Bernoulli's equation, Coulomb's law, Michaelis-Menten, Hess's law, the Doppler effect. Named means fair game. You should know what each one describes and which direction its variables push.

What Gets Handed to You

Here is the part that should lower your blood pressure. Several prep sources, including MCAT-prep.com and MedLife's physics guide, note that the AAMC occasionally supplies physics formulas inside a passage, and that it never supplies the basic ones.

That gives you a workable rule for the whole exam. The foundational equations come out of your memory, and the exotic ones tend to arrive inside the passage that needs them.

So sort everything into three tiers. The 18 written-out equations plus the named workhorses go in the know-cold pile. Other named relationships get learned as relationships, meaning what goes up when something else goes up. Everything past that, you learn to recognize when a passage introduces it.

Memorize the Exponent

MedLife's guide, the one with 190 equations, makes the single most useful observation in this entire genre: most questions care whether you know what happens to one variable when another one moves. Sketchy's equation guide says the same thing with the classic example. Velocity doubles. What happens to kinetic energy?

This is where the exponent does all the work.

Double the radius of a blood vessel and flow climbs sixteenfold. Double velocity and kinetic energy quadruples. Double the distance between two charges and the force drops to a quarter. On test day, the exponent is usually the whole answer.

The method for getting all of this into your head is unglamorous. Write the equations out, by hand, from memory. A 2007 meta-analysis in Memory & Cognition pooled 86 studies of what psychologists call the generation effect and found that producing information yourself beats reading it by almost half a standard deviation. Staring at a formula sheet is reading. Writing the formula cold is generating.

For the record, PurpleCAT's formula library groups every equation by AAMC content category with notes on when to reach for it, and lets you star the ones that keep slipping. The Formula Writing Drill asks you to produce each one from its name or a scenario before you flip to check.

The summary of my investigation, then. Memorize the 18. Understand the named ones by the direction they push. Write everything by hand. Stop worrying about number 190.

Sources

• AAMC, Chemical and Physical Foundations of Biological Systems outline
• Student Doctor Network, MCAT Equations
• MedLife Mastery, MCAT Equations Sheet
• MedLife Mastery, MCAT Physics Equations
• MCAT Self Prep, MCAT Equations: Should I Memorize Them?
• MCAT-prep.com, MCAT Physics Equations Sheet
• Sketchy, MCAT Equations: What to Memorize
• Bertsch et al., The Generation Effect: A Meta-Analytic Review (2007)