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Top Strategies for Mastering Market Sizing Questions

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November 2, 2021
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5 minutes
Gizela has almost two decades of experience within the Digital sphere and eagerly awaits the day she can be cloned so she can finally get everything on her daily to-do list done

Interviews can be daunting at the best of times, but nothing can throw you off your game such as the question “How many bicycles are in Beijing?” And that is essentially the nature of market size questions.

For those who are unsure of what market size questions are, it is pretty much a guessing game: The interviewer will ask you to estimate the size of something and will give you little to no context or data.

Does this sound like any consultant’s worst nightmare? Probably. But there are a few case study themes that are particular favorites. As long as you prepare and arm with the how-to knowledge and examples we’ll dive into shortly. You don’t need to enter the interview room fearing that they will ask 'how many turtles are on the beaches of Mauritius and how to solve the problem'.

What are the interviewers looking for?

Many consultants make the mistake in thinking that particular case studies that interviewers are the most fond of asking comes with ready-made answers that they can simply study and recite during the interview. But this is not what one should be doing at all. The entire purpose of asking these consulting interview questions is so the interviewer can evaluate your thought process.

You will need to:


Break the question down into the various components needed to make the assumption.

Assume them all

Give the interviewer an assumption for each of these components.


Finally, give an overall estimate to the question when taking all assumptions into account.

Half of science is asking the right questions.” – Roger Bacon

Supply vs Demand

One of the first things that you will need to establish is whether you need to answer the question from the supply or demand side. If it is from the demand side, you can use the Filter Formula in order to make your assumption. If it is from the supply side, you can use the Supply formula.

Filter Formula

Market Size = Baseline (Total population in location) x Ratio (Portion of baseline to be included in estimate) x Frequency of Purchase (Average purchases in set amount of time) x Quantity per Purchase (Amount of units bought each time) x Price (Price of product per unit)

Supply Formula

Market Size = Total Number of Suppliers (The total number of suppliers in the specific market) x Max. Capacity per Supplier (The production capacity of supplier in certain period of time) x Capacity Utilization Rate (The maximum production capacity that is actually reached by a supplier) x Price (Price of product per unit)

Ask Questions

Just because the interviewer is tasked with asking the consulting interview questions doesn’t mean that you can’t. In fact, interviewers are looking for applicants who can take initiative, spot gaps and have the knowledge to avoid pitfalls. These are some of the questions you can ask that may apply to your specific set of market size questions:

What is the unit of measurement?

There is a big difference between market volume and market value. Market volume relates to the amount of something and market value points to how much something is worth.

What is the time period?

The answer to “How much fruit is being exported?” can drastically change in terms of a week, a day or a year.

Which location ?

Once again, the fruit export question’s answer can change dramatically when looking only at specific regions, cities or countries compared to globally.

What’s the product detail?

Making estimates regarding handbags can be one thing, but any woman will be able to tell you that there’s a big difference between buying a Gucci bag vs. a Walmart bag or a cotton bag vs. a leather bag. As the old adage says: the devil is in the details. Especially when it comes to consulting interview questions.

Who’s the target audience?

Exactly who the product or service is intended for plays a major role. Are they selling to businesses or private individuals? Are they children or adults? Male or female? There are so many things to consider when defining a target audience and you’ll need to consider this when answering consulting interview questions.

What are the distribution channels?

Are you considering only online or offline sales? Should you take only word of mouth marketing into account or just online paid ads? Are you focusing on wholesale or retail? All of these will also impact your answer.

Market Size Practice Questions

As we mentioned earlier, interviewers definitely have a few favourite themes when it comes to market size questions, so we have compiled a handy list of market size practice questions to help prepare you for your consulting interview questions:

Long-form Market Size Practice Questions:

The Big Breakfast Question

Your client has been fairly famous for their pub lunches, but lately they have been thinking of offering breakfasts too. They would like you to figure out whether there is a market for this. The only information/data that I have available for you is that 25% of the country’s population eats breakfast, 30% of those eat at home and the other 70% eat out (50% grab breakfast on the go on their way to work and the other 20% bring it home).

The Dating Question

Your friend just broke up with her boyfriend. She is overwhelmed with how many fishes really are in the sea. Estimate how many eligible bachelors are out there for her.

Shorter Market Size Practice Questions:

  • What is the market size of toothbrushes in the UK?
  • How many Samsung mobile phones are sold every year globally?
  • How many individuals in the US buy life insurance policies?
  • What is the market size for contact lenses?
  • Can you estimate how many sales an Apple Store makes?

Interviews don’t have to be so stressful if you come prepared. Moreover, mastering market size questions doesn’t need to be such a big deal if you come armed with knowledge and market size know-how. Follow our above mentioned advice and some of our other helpful interview tips and tricks for consultants here, and we’re sure that you’ll blow the interviewer away!