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Does McKinsey doing market size questions?

In the McKinsey casing interviews do they do general market size cases through estimation like in Bain, etc.?

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Patrick
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on May 06, 2026
Ex-McKinsey and Roland Berger; I get you consulting-ready ✌️

Brainstorm market sizing: nearly never -  Creating a bottom up estimation of a market by taking extensive assumptions from your personal experience is very rare in McK cases. Instead of such brainstorming approaches they focus on the below mentioned market sizing via given numbers. 

Market sizing in general: yes absolutely - Having to do market sizing via different routes (e.g., top down or bottom up) is a common part of a McK case. However, the numbers are given by the case via exhibits, interviewer prompts or previous case sections.

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Tommaso
Coach
on May 06, 2026
Ex-McKinsey | MBA @ Berkeley Haas | Market Sizing Master | 50% off on 1st meeting in May (DM me for discount code!)

Hey there,

The answer is a strong yes: I would say that roughly 60-70% of McKinsey R1 cases involve some kind of market/opportunity sizing. Most of these are top-down, but tougher interviewers do expect you to handle a more complex bottom-up market sizing (although, more typically in R2)

Please, note that this can mean a combination of a few different things:

  1. A case that focuses purely on market entry -- and where market sizing can take up to 30-40% of the time
  2. A quick question on the size of our client's market in a different case type
  3. The calculation of an investment opportunity, e.g., where you launch a new product and you need to calcolate a P*Q starting from the market size (for example using then some penetration rate
  4. The calculation of the client's revenue, similar to the point above

Hope this helps!

Tom

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Franco
Coach
on May 06, 2026
Ex BCG Principal & Global Interviewer (10+ Years) | 100+ MBB Offers | 95% Success Rate

Building on Patrick’s response, also note that market sizing is usually embedded within a broader case. It’s very rare to get a standalone market sizing question.

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Jimmy
Coach
edited on May 06, 2026
McKinsey Associate Partner (7 Years) | McKinsey Recruiter | 500+ Interviews | INSEAD MBA

As a McKinsey interviewer for 7 years, let me share my 2 cents! :)

Yes, absolutely!

Especially in Round 2. And here's why:

- Round 1 usually taken by an Associate or EM. They come prepared with a structured full length McKinsey case from the Firm Case Library. Very unlikely to be a full on market sizing case

- Round 2 usually taken by an AP or Partner. It is perfectly possible that the Partner or AP did not come prepared with full length exhibits or cases. (especially back when interviews were in-person). So that means    --> They don't have any data off-hand --> Meaning you have to create the data --> Meaning it becomes a de-facto market sizing case! So, YES!

When I interviewed as a candidate with McKinsey, I had a total of 7 cases, of which two were full-fledged market sizing cases (so please do not ignore them, especially in Round 2) - hope that helps!

Cheers
Jimmy

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Ashwin
Coach
on May 09, 2026
Ex-Bain | Help 500+ aspirants secure MBB offers

Short answer, yeah they do, but the flavour is a bit different from Bain or BCG.

McKinsey does include market sizing, but rarely as a standalone case. It usually shows up as part of a bigger problem, like sizing a customer segment within a market entry case, or estimating a revenue opportunity inside a growth case.

The style is different too. Less estimation gymnastics, cleaner setup, quicker turnaround. They're not really looking for a perfect number, they care more about whether your logic is structured and your assumptions make sense.

So if one comes up, lay out your structure first, walk them through it before computing, anchor each assumption with a quick reason, and sanity check the final number at the end.

Good luck.

Profile picture of Cristian
on May 06, 2026
Professional MBB coach | Published success rates: 63% MBB only & 88% overall | ex-McKinsey consultant and faculty

Hi there, 

Yes, they do. 

They might not be self-standing, as in just a market-sizing question. Typically, they are embedded in the case itself. 

But even if they weren't specifically part of the interview process, I would still recommend you practice them, because they combine so many of the skills that use for other elements of the case: structuring, estimating, aligning with the interviewer, computations, etc. 

If you need any help with this, drop me a line.

Best,
Cristian

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Mauro
Coach
on May 06, 2026
Ex Bain AP | +200 interviews | 15years experience | Top MBB coach

Usually not as standalone cases.

At McKinsey & Company, market sizing is most often embedded inside a broader strategic case. For example:

* estimating market potential

* sizing a customer segment

* calculating demand to support a recommendation

So you still need to be comfortable with estimation, but it’s rarely “how many tennis balls fit in X?” for 20 minutes straight. It’s typically tied to a business problem.

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Soh
Coach
on May 07, 2026
Lifesciences industry expert | Ex-ZS Interviewer | Global Commercial Strategy | M&A | 15m free intro | 10% off 1st case

Hi,

Yes, you may have to size a market as part of the broader case, but mostly not a market sizing case where you have to come up with your own assumptions.

For example, you may be asked to estimate revenue for a drug and given the assumptions that you use to estimate. The catch can be in the form of how you estimate dosage etc.

Hope this was helpful.

Thanks,
Soh

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Alessa
Coach
on May 06, 2026
10% off 1st session | Ex-McKinsey Consultant & Interviewer | PEI | MBB Prep | Ex-BCG

hey! 

as someone who interviewed at McKinsey myself, I can confirm they use sizing mainly to test structured thinking, realistic assumptions, and clean math inside a broader case flow => so only embedded in a case. BCG & Bain love market sizing :) 

Alessa