How to prepare for the McKinsey Case Interview - 7 essential tips

In this article, we highlight the 7 important considerations for your case interview preparation for McKinsey that help you ace the case interview. We particularly highlight the specifics of the McKinsey interview as it slightly deviates from the case interviews you see at BCG and Bain.
Dec 15 / Case Interview Hub

#1: Focus on interviewer led cases

The case interview at McKinsey is interviewer-led. In this format, the interviewer steers the interview more strongly compared to the interviewee-led (also known as candidate-led) interview. This means that the interview follows the following structure:
  • Structuring question
  • 3-4 questions testing your skills (to learn more about the tested skills check out our extensive case interview guide)
  • Synthesizing question
As you can see based on this interview structure, the concrete questions the interviewer is going to ask are already predetermined before you walk into the interview.
This has implications on how to approach the interview. For the structuring question, this means that you will not be able to decide yourself which branch of your issue tree you are going to explore first. Instead, you should let the interviewer know which branch you would explore first after you have presented your structure. This shows that you are thinking ahead and that you are still driving the case. But the next question after the structuring is already predetermined and you can’t influence it.
The interviewer-led format also has implications for the follow-up questions. As the 3-4 questions are already predetermined it is likely that they have a twist to them. For example question 1 could be a chart that leads you into a certain direction. But question 2 could later reveal new information that leads to a different route thereafter. So in the interviewer-led format, you should pay particular attention to potential twists in the case as new data is presented.
The synthesizing question is the same in all case interviews, so there is nothing in particular to mention for the interviewer-led interview. In short, state a clear recommendation with 3 supporting arguments, repeat the recommendation. And for a great conclusion of the case also mention the next steps. But more on that in our article on case essentials.

#2: Use authentic cases

We often hear at recruiting events and from candidates that they prepared with some - let’s call it questionable - resources. Here is a list of the preparation material we mean:
  • Outdated case books from business schools
  • Case books with outdated or too complex cases (e.g., because they are meant to be solved in written form)
  • Cases from peer platforms online
All these materials have the issue, that the cases often have little in common with what you see in your case interview. They tend to have they problem that they are either too long or too short or too complex or too simple. And they are often prepared by people  preparing for case interviews themselves and not by experienced interviewers or consultants. Additionally, they often don’t have detailed solutions including feedback on why the case is solved in a certain way.
Don’t get us wrong, these cases can be useful for your preparation. But only for specific things. You should use these materials to practice specific parts of the case interview. For example, you can just use these cases to structure the issue tree and later validate your structure with the sample solution (if there is any). Furthermore, you can use these cases for practicing your case math and, if the cases are good, increase your knowledge about an industry.
Further, you can also leverage this material for your peer practice. Usually, if you practice live cases, your case buddy and will alternate the roles of interviewer and candidate. Thus, you also have to prepare a case that you can give to your buddy. You can leverage the bad cases to just build your own case that you can then let your buddy solve. However, a word of caution on this. If you are not experienced with case interviews at consulting firms, it is likely that the case you create is far from what you would see in an actual case interview. So if you like your buddy, it is better to let him or her solve authentic cases.

#3: Don’t overemphasize memorizing standard frameworks

If you have googled case interview preparation, you surely stumbled upon standard frameworks for structuring the case (i.e., the issue tree). There are even books out there that teach the “essential” 20 frameworks you need to memorize to pass the interview. Candidates often memorize these frameworks and hope that by doing that, they can quickly create a MECE issue tree. What usually happens as a result is that they apply super generic frameworks to a case or try to squeeze the case into a certain framework they memorized. Be assured that the interviewers at McKinsey heard the standard frameworks 100 times and will recognize right away if you are just parroting a framework that you have memorized. Candidates are then often surprised that they didn’t pass the interview.
What you should do instead is to have a look at all these frameworks and understand why they are structured a certain way and what makes them MECE. By doing that, you will memorize the backbone of some of the basic frameworks. And later on for each case you are solving you can tailor the framework and add points for the specific industry of the respective case. Check out our case interview guide to learn more about frameworks and on how detailed your issue tree should be.

#4: Realistic preparation

This point goes to a certain extent hand in hand with our point on using authentic cases to prepare for your interview. Not only should you do that but you should also practice cases in a realistic scenario.
You should not solve the case in silence. In an actual case interview, you have to talk the interviewer through your approach and solution. And this requires practice. Trust us, we have seen many candidates that only prepared cases without practicing how to actually talk through them. And if your interview is the first or second time that you have to walk an interviewer through the case, it is very likely that it will be tough for you and the interviewer will notice that you are insecure. Does that mean you should only practice in a realistic interview setting? No, not necessarily. You can do structuring drills and math drills in silence. But if you actually want to get the most out of them you should treat those drills like an actual interview, even if you are just by yourself. Talk the imaginary interviewer through the structure and through your math. This will help you tremendously even if it feels silly at first.
Additionally, you should try to find a mentor that can coach you and give you insider tips. Ideally you know an interviewer at McKinsey or at least someone who works there. If you can solve 3-5 cases in an interview setting with that person it will give your case practice a tremendous boost as you will realize right away which parts of the case interview you are strong in and on which areas you need to work on. Moreover, if the person is a current or former interview at McKinsey, he or she can also give you an indication on whether your performance was good enough to pass this specific case.
If you don’t know anyone at McKinsey you should consider getting a coach. Even though this can be very expensive it will definitely turboboost your preparation if it is a good coach. Make sure to do your due diligence on the coach as there are many proclaimed former McKinsey consultants out there that have never set a foot in the firm. The high price tag of a good coach might let you hesitate but remember that this interview could be your only chance to get a job at McKinsey. And compared to the time and money you spent into your degree the costs for a coach are likely minuscule. We touched upon whether it is worth it to spend money on interview preparation in this blog article.
If you are looking for a cheap way to practice cases feel free to check out our case interview simulation. Our cases are prepared by McKinsey consultants and each case includes a case simulation where you solve the case yourself as well as a sample solution (you can follow a candidate how she solves the case incl. following her trail of thought) and a detailed feedback solution (where you get insider tips and rationale why the candidate approached the case a certain way and what the candidate did good and why). Each case comes with ~2 hours of video material. Try it yourself - the first case is for free (no strings attached).

#5: Don’t neglect the Personal Experience Interview (PEI)

Even though this article is about how to prepare for the case interview at McKinsey, we have to mention the Personal Experience Interview (PEI) also known as personal fit interview. If you don’t know what we are referring to by PEI or personal fit interview check out this article on personal fit.
We see many candidates solely focusing on the case interview and then ending up winging the PEI. And as you can imagine, this can go south relatively quickly. The reason for that is that the PEI is a core component of the McKinsey interview, taking around 20 min. This means that the PEI part is only slightly shorter than the case interview (~30 min). As interviewers, we have seen many candidates acing the case interview and then telling stories in the PEI that had nothing to do with the tested dimension or that had little to no structure. It often felt like listening to that one friend that tells long stories without getting to the point so that you end up wondering what this was even all about.
So should you prepare the PEI as extensively as the case interview? No, definitely not. The PEI is important but as long as you have your stories ready, well structured, and they target the tested dimensions you are fine. But we highly recommend to not just walking into the interview and winging it. Especially as McKinsey lists the tested dimensions on their homepage (https://www.mckinsey.com/careers/interviewing):
  • Personal impact
  • Entrepreneurial drive
  • Inclusive leadership
  • Courageous change
This allows you to prepare 2-3 stories per dimension so that you have a story for each interview as well as a back up in case the interviewer asks you to tell another story. 

#6: Take enough time to prepare

Taking enough time to prepare for your case interview as well as PEI is crucial. So on to the age old question: How many practice cases should you do?
If you are already quite good at cases due to prior experience or just because you have a talent for solving them then you should be fine with doing 10 high quality. But it’s probably better that you do 20 or more to be on the safe side. By quality cases we mean authentic cases practiced in a realistic way - so the points we are referring to in the paragraphs on Use authentic cases and Realistic preparation. 10 cases won’t cut it if you are reading through 10 business school cases in silence and then head right to the McKinsey interview.
For someone without a god-given talent for doing case interviews, the number of cases you should practice should be much higher and you should aim for around 50 cases. 50 sounds a lot but hear us out. There are many variables in a case interview given different industries, topics, and question types. So after 30 cases you should feel comfortable that you have already seen a variation of everything you can come across in the case interview. And after 30 you can start refining individual aspects of your case skills with solving cases becoming part of your muscle memory. Moreover, if you are that well prepared, even when you have a bad day you should be able to ace the case interview.
So how much time should you set apart to prepare 50 cases? Well, first you need a case partner or book time with a coach. If you want to do 50 practice case interviews with a case partner you need to set aside around ~2 hours per practice session. The reason for that is that you will likely interview each other back-to-back and also have to set time aside for feedback. If you manage to do such a session each day it still will take you around 7 weeks to get to 50 cases. We are assuming one interview per day as you should also set time aside to review your mistakes and prepare the PEI. So you should definitely start preparing 2 months before your interview day.
If you have less time it is also doable but it is going to be much more of a challenge and you probably will need to work with a coach or already have a very dedicated and good case partner. Cramming in 50 cases in 2 weeks will be challenging if you are working in a full time job (e.g., during your summer internship) or while you have much to do for completing your degree, given that you need to do ~3 cases per day. And while doing that you still have to prepare for the PEI . We definitely don’t recommend setting aside only 2 weeks for preparing for your McKinsey interview. This is your chance to get a highly attractive job at a leading strategy consulting firm. You should really dedicate yourself to mastering the interview and plan accordingly.  
So the best case scenario is 2 months of moderate practice, investing not more than 2-3 hours per day. Then you have more than enough time to practice cases, review your mistakes, prepare the PEI, practice mental math, and you can also build business judgement and industry knowledge, by getting your daily dose of business news.

#7: Don't overpractice

Given that we highlighted the importance of preparing enough cases, a final word of caution. If you are approaching 100 authentic cases in a realistic interview setting you might wanna consider focusing on reviewing your mistakes and preparing the PEI. You will likely reach a point of diminishing return when you are approaching 100 cases, where you don’t improve anymore. We still hear the voices of many candidates at recruiting events in our head, proudly telling us that they practiced more than 100 cases in the last months. The main problem here is not that you prepared too much and will thus get worse but that with that much time invested, they put the job at McKinsey on a pedestal. And once the interview day rolls around, they are so nervous, and tense, that their case performance suffers or they get depressed if they don’t get the job due to a mistake during one of the cases. With 50 or 60 good cases under your belt, you should feel more than comfortable, even at the most competitive firms. And the time you save by not preparing 100 cases is better invested into working on the PEI, your business judgement, or simply enjoying yourself. A job at McKinsey is a great career start but it is not your main purpose in life.
If you want to learn more about how to best prepare for your interview, check out our YouTube channel where we have a dedicated preparation roadmap and additional content on how to get into consulting: https://www.youtube.com/@CaseInterviewHub