How common are market sizing questions in MBB interviews?

Market sizing
New answer on Dec 31, 2021
4 Answers
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Anonymous A asked on Dec 02, 2018


Do you know how common market sizing questions in MBB interview?

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replied on Dec 02, 2018
Bain & Co interviewer (~3 years) | MBB-prep focused | Expert: Market Sizing; P&L cases | 50+ coachees at MBB


Great question!

I might be talking about Bain only, but having a case exclusively focused on market sizing at Bain is extremely unlikely. When we "create" our cases, we have clear guidelines, and market-sizing only cases don't give us a chance to evaluate candidates across all dimensions.
This being said, you can definitely have a market sizing "sub-question" in a P&L or revenue growth case for instance, and I would guess this happens in 10-15% of the time, and certain offices may be more likely to give market sizing than others.

I have also heard that BCG (at least in London) is trying to tweak the format of the first rounds and include necessarily a market sizing there - not sure if this is systematic and if this is the case in other offices.

I haven't heard that McK are necessarily big fans of market sizing, and I expect an approach similar to Bain, you may need to size a market but that would be part of a broader question - again to be verified for the office you're targetting.

Overall, I'd say the best way to know this would be to ask a few consultants from the office you're interested in at MBB and compare their answers.

I hope this helps! :)

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replied on Dec 03, 2018
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School


Quite common among all the three firms. More often as a part of the case than as a standalone case. The actual frequency does not matter - it's just to often to neglect the market sizing cases in your preparation.


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Content Creator
replied on Dec 31, 2021
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate

Hi there,

Providing some market sizing thinking for anyone revisiting this Q&A:

Remember that there's rarely a "best" answer with market sizing. What's important is that you break down the problem the way it makes sense to you. Importantly, break it down so that the assumptions you make are the ones you're most comfortable in.

For example, do you know all the major brands? Great go with that. Do you understand all the segments of that country's population (either age or wealth or job breakdown)? Go with that. Do you know the total market size of the tourism (or hotel) industry? Then break it down that way.

Some tips:

  1. Just like in a case, make sure you understand the question - what are you really being asked to calculate
  2. Decide whether a top-down or bottom-up approach is best
  3. Figure out what you know you know, and what you know you don't know, but could estimate
    1. This helps you determine how to split out buckets
  4. Stay flexible - you can start with a "high-level" market sizing, but gauge your interviewers reaction....if it looks like they want you to do more...then go along level deeper in terms of your splits
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replied on Dec 02, 2018
Ex-MBB, Experienced Hire; I will teach you not only the how, but also the why of case interviews

Fairly uncommon, especially at BCG and McK in my experience. Bain may give them a little more often apparently, but I'd still rate as rather unlikely

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Ben gave the best answer


Bain & Co interviewer (~3 years) | MBB-prep focused | Expert: Market Sizing; P&L cases | 50+ coachees at MBB
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