McKinsey Second round most random questions and hardest market sizings

interview questions Market sizing McKinsey 2nd Round
New answer on May 20, 2022
4 Answers
Anonymous A asked on May 17, 2022


I have my second round McKinsey next week and would love to hear

1.) The hardest case questions you have experienced / asked in such an interview

2.) The hardest market sizing questions you have received / given


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Content Creator
replied on May 18, 2022
#1 rated McKinsey Case and PEI Coach | 5 years at McKinsey | Mentorship Approach | 120+ McK offers in 18 months

Hey there,

There is no McKinsey 2nd round case, same as there is no McKinsey 1st round case. In theory, they are all created based on the same guidelines to assure a certain level of objectivity.

Regarding your questions:

1. Creative second round case

One of my second round cases from a couple of years ago was along the lines of ‘’Our client manufactures and operates check-in machines at airports in the USA. The machines break down at different rates in different locations. What could be the reasons for this?'' 

This was a typical McKinsey-style creative case, where frameworks will not get you very far. The same types of cases also have to be expected during the first round.

2. Market sizing

McKinsey usually does not do market sizing as it does not fit the format of an interviewer-led case and the evaluation criteria that go with it.

3. My general thoughts on 2nd round interviews

95% of McKinsey partner rounds are just as standardized as the first round, yet be prepared to expect everything. Sometimes they are more conversational and friendly, only with light-touch evaluation, other times they are more challenging. Usually, they are the same. 

The reason why you read about freestyle partner experiences is that they deviate from what people expect, hence they post about it more frequently online, hence giving others the impression it is much more common.

Additionally, partner rounds are often perceived as more challenging, just because it's a partner sitting across the table rather than a more junior colleague. It is purely based on the impression and not on the content. :-)

If there are any deviations from the standard interviewer guidelines, expect them to be in the following realm:

  • Focus on one or two areas where you were perceived as not as strong in round one, which can be specific case questions or fit questions (or PEI for McKinsey)
  • Only doing a case, only doing fit instead of both
  • Doing two shorter cases in quick succession
  • Challenging your answers more
  • Not providing any time for you to think about the answer, making it more conversational

In any case, the most important thing is not to be startled by this and just keep working on the case and fit in a calm manner. 

Have a look at the following two articles that I wrote or reach out for McKinsey-specific coaching:



All the best for your second round!


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Anonymous A on May 18, 2022

amazing, thanks so much!

Content Creator
replied on May 18, 2022
MBB | 100% personal interview success rate (8/8) and 95% candidate success rate | Personalized interview prep

Hi there,

Remember that what's difficult for one person might be easy for the other, and vice-versa!

A few recent questions I've liked are:

  • A city in x country is looking to create a new district close to a tourist site with expected strong growth. Help the city define the retail offer.
  • Your client is a leading retail bank offering residential mortgages, among other financial products. The overall number of mortgage applications that were started last year increased, however, the number of completed mortgages decreased. The CEO has asked for your help in identifying a solution to this problem
  • How many visas did x government print this year 
  • How many people are actively using the internet right now

Good luck!

Here's some more info on casing mindset:

Here's some more info to prep for fit:


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Content Creator
replied on May 20, 2022
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut


+1 to Florian here, the guidelines that case writers (interviewers in most cases) follow in order to create both 1st and 2nd round are the same. 

To your question, and given that market sizing cases were the topic of many questions in this Forum, I developped a market sizing case, that you can find for free in PrepL´s library

Let me know if you have any doubts with it, it contains a detailed explanation and methodology about how to solve this specific example, but you can extrapolate to many other market sizings!



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Content Creator
replied on May 17, 2022
Ex-McKinsey London final round interviewer

There used to be a McKinsey partner who led the BA programme always ask “calculate the square root of 2”.  

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Florian gave the best answer


Content Creator
#1 rated McKinsey Case and PEI Coach | 5 years at McKinsey | Mentorship Approach | 120+ McK offers in 18 months
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