Does unit choice matter in market sizing questions?

Yes, it is absolutely acceptable to use metric units in U.S.-based consulting interviews, as long as your assumptions are clear and the math is internally consistent. Interviewers care far more about logic and structure than the unit system.

Just make your assumptions explicit (e.g., “I’ll assume a standard door is ~1 meter wide and scale from there”). That’s perfectly fine.

That said, it’s still useful to know a few rough conversions in case you’re given non-metric numbers: 

• 1 inch ≈ 2.5 cm
• 3 feet ≈ 1 meter (roughly) :) 

Pro tip: always do a quick reality / sanity check at the end of your calculation (if possible). Remembering anchor numbers like population sizes, GDP per capita of major regions, or typical revenue ranges for mid-size vs. global companies helps you calibrate your result, boosts confidence, and shows strong business judgment :)

Hope this helps!!

That's a very pragmatic question, and I'm glad you're focusing on elements that simplify your mental math under pressure.

Here is the key insight: In a market sizing case, the interviewer is scoring your structure, the clarity of your assumptions, and your ability to execute the math without errors. The specific unit system you choose is almost completely secondary to those three criteria. You will not lose points simply for using meters instead of feet, provided you are perfectly consistent throughout the case.

However, there is a subtle practical friction to consider. Since US-based firms and clients overwhelmingly operate in the Imperial system, using metric forces the interviewer—who is grading you in real-time—to make a constant mental conversion to check if your assumptions feel reasonable (e.g., is "2 meters" a realistic height for a door?). This cognitive burden takes their attention away from the core structure, which is where you earn the bulk of your score.

The strategic solution is simple: If you are genuinely uncomfortable with imperial proxies, use the metric system, but make a crystal-clear declaration upfront: "For simplicity, I will conduct this sizing in metric units, but will ensure all figures are clearly stated." Crucially, you should also simplify your base numbers drastically. Regardless of the system, use round numbers that make the math trivial (e.g., 300 million people, 3 meters per floor, 50 weeks per year). Clarity and roundness always trump native convention.

All the best!

hey there :)

Yes that is totally fine and very common. Interviewers care about structured thinking, clear assumptions and consistent math, not the unit system itself, so using metric units is absolutely acceptable even for US firms as long as you state it clearly and stay consistent. I have seen this many times in interviews and it was never an issue. Feel free to reach out if you want to practice a sizing together.

best,
Alessa :)

Hi there,

Unit choice does not matter in market sizing questions. It’s perfectly acceptable to use metric units even when interviewing with U.S.-based firms, as long as you are clear about your assumptions, consistent throughout the calculation, and explain your logic clearly.

Interviewers care far more about your structure, reasoning, and communication than the specific units you choose. 

Best,
Evelina

Yes, totally fine. Use metric if that is what you know.

What matters is clear logic and clean math, not which units you use. Just say upfront, "I am more comfortable with metric, so I will work in meters." No interviewer will penalize you for that.

The only thing to watch: if the interviewer gives you data in feet or inches, make sure you convert correctly or ask if you can restate it in metric. Do not let unit confusion mess up your calculations.

You are good. Use what you know.

I would recommend you clarify this directly with the interviewer. 

By default, you should use whatever system is relevant for that geography e.g., imperial in the US, metric in EU.

But this is never a problem. It's not part of the 'assessment' per se. 

Best,
Cristian