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Unit Hack for the MCAT® exam

A simpler
way to solve.

Units first. Math last.

MCAT Chem/Phys calculations can be overwhelming when you don't know where to start, even if you know the content.

Unit Hack teaches you a simple, repeatable six-step method to identify what quantity you're solving for, isolate the information you need from the passage, and build a setup you can check before doing actual calculations.

Before you reach for a formula, read the units.

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6method steps
25core lessons
323Practice Bank questions
83Practice Bank passages

The six-step Unit Hack method

The wave example above shows the method in action. Try each step with a different calculation: a resistor has 6.0 V across it, carries a steady 2.0 A, and operates for 5.0 s. How much electrical energy does it dissipate?

Target

Identify the requested quantity and target unit before using the values.

Electrical energy → J
The question asks for energy dissipated by the resistor, not power, current, or voltage.

Decode

Break the target unit into equivalent forms. Choose the form that connects to the quantities in the question.

JV × CV × A × s
SI base units:
J=kg · m2s2

Breaking a derived unit into base units shows the dimensions underneath it. You don't need the full SI breakdown every time: here, V × A × s is the useful equivalent form because the passage gives voltage, current, and time. A coulomb is an ampere-second (C = A·s).

Collect

Identify the relevant givens and conditions in the question.

ΔV = 6.0 V · I = 2.0 A · t = 5.0 s
The resistor operates at a constant voltage and current for the stated time. All three values are relevant to electrical energy.

Build

Arrange the relevant givens so their units lead to the target before substituting any numbers.

Arrange voltage, current, and time to build joules. Write their units as fractions before using any numbers.

JC×Cs×s1
The unit pattern points to voltage × current × time. For a constant-current resistor, the electrical-energy relationship justifies this setup.

Cancel

Check that the proposed setup reduces to the target unit.

Now cancel the matching coulombs and seconds across the fractions.

JC×Cs×s1→J
Only joules remain. The unit check confirms the dimensions—not, by itself, that the physical law is correct.

Check

Calculate, then check the unit and physical meaning.

6.0 × 2.0 × 5.0 = 60 J
The resistor dissipates 12 W (6.0 V × 2.0 A). Over 5.0 seconds, that is 60 J of energy.

You know the science but you're still stuck on the setup?

A passage can make sense while the calculation still feels unclear. You might not know which quantities matter, how to arrange them, or how to finish the math without a calculator.

Trying to remember every formula

You recognize the topic but can't remember which equation applies. Sometimes the units can help you reconstruct the relationship.

Not knowing how to set up the problem

The passage gives several quantities, and you're unsure which ones matter or how to arrange them.

Getting tangled in units and conversions

A prefix, unfamiliar derived unit, or inverted ratio can throw off an otherwise correct calculation.

Doing the math without a calculator

Scientific notation, fractions, logarithms, and estimation can be difficult under time pressure.

Units help with the setup, but they don't replace the science. Some problems still require a specific equation, constant, or information from the passage. Unit Hack helps you recognize when dimensional analysis is useful and when another approach is needed.

What you work through

The course starts by teaching the six-step method, then shows you how to apply it across common Chem/Phys calculations. You'll also learn techniques for handling the math and practicing the method under test-day conditions.

PHASE 01Core ReflexLessons 0–9

Learn the six-step method, practice building calculations from units, and work with prefixes and scientific notation.

PHASE 02Unit DecoderLessons 10–15

Learn the unit relationships used in mechanics, electricity, fluids, waves, thermodynamics, and chemistry.

PHASE 03Tactical ToolsLessons 16–18

Practice reading graphs and tables, estimating answers, and handling fractions and logarithms without a calculator.

PHASE 04Test-Day ExecutionLessons 19–24

Apply the method to mixed problems, learn where dimensional analysis has limits, and review mistakes systematically.

PRACTICEPractice Bank323 questions · 83 passages

Apply the Unit Hack method to 323 questions across 83 passages, including problems you haven’t seen before. Use the bank to practice recognizing the target unit, constructing a setup, and checking your reasoning.

Quick DrillsFocused setup practice

Revisit individual unit relationships and practice arranging quantities before returning to longer questions. Use these when one part of the six-step method needs reinforcement.

Math ClinicsFour focused clinics

Work through four focused clinics covering the arithmetic used in MCAT calculations without a calculator. Return to them when the setup makes sense but the numerical step still slows you down.

Why I built Unit Hack

I was frustrated that this took me so long to learn.

I could understand the science, know the relevant formulas, and still get stuck turning a dense Chem/Phys prompt into a setup I trusted.

I kept finding more resources and more formulas, while also hearing the same advice: use dimensional analysis, use the units. That advice was correct, but I did not have a repeatable way to apply it.

I started rewriting units into useful equivalent forms, mapping the relationships I kept needing, and drafting workbook pages so I could practice the process deliberately. That workbook came first. Unit Hack is the more developed version of the same idea: an interactive mini course built so students can understand the method faster and get dedicated practice instead of piecing it together alone.

Reference chart from an earlier Unit Hack workbook showing quantities, units, base-unit expressions, alternative forms, and key words to look for.
From the earlier workbook · reference chart
This was part of the first attempt to organize the unit relationships into something I could actually use and practice.Swipe horizontally to read the full chart.

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Work through a complete introductory lesson, try the method on an MCAT calculation, and see how the explanations work.

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