Starting case interviews preparation

Case Interview preparation
New answer on Jun 12, 2020
11 Answers
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Anonymous A asked on Jun 06, 2020

Hello! I would like to start preparing for case interviews, I have already bought 3 books (Case interview secrets by Victor Cheng, Case in Point by Cosentino and Interview math by Lewis Lin) but I still feel that I don't know how to prepare in a good way because those books are or too theoretical or way too practical without a generic expaination.

So, how can I improve? May someone suggest another book or website which can give me a sufficient preparation? Thanks!

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Content Creator
replied on Jun 06, 2020
McKinsey offers w/o final round interviews - 100% risk-free - 10+ years MBB coaching experience - Multiple book author

Hi Anonymous,

There is already good "content" advice on how to prepare for interviews. Looking at this question more from a "process" point of view and assuming that the candidates starts his prep in due time, this is what worked for most of my coaching candidates (I see you already did the first steps of those!):

  • Starting off with basic case interview books like Marc Cosentino's "Case in Point" or Victor Cheng's "Case Interview Secrets"
  • At the same time watching Victor Cheng's youtube videos
  • Getting a professional case interview coaching, like here on PrepLoungequite early in the process, as a professional case interview coach will help you get things right immediately, so that you can focus on your weak spots and at the same time reinforce your positive habits during your further prep
  • Start having interactive mock interviews with peers, which you can find in masses also on PrepLounge - there is a strong correlation between number of interactive cases solved and interview success; I occasionally also do professional case interview coachings myself (Case Interview Coaching)
  • Once you feel you make progress in your case interview performance, start having some professional coaching sessions again to get some real-life benchmark and feedback for further improvement; what works best is approx. 1 professional coaching per week as there is enough time to improve weak spots with peer mock interviews until the next coaching, and at the same time this timeframe is short enough so that you keep up with you prep and do not lose track
  • Once you start feeling comfortable with solving cases in general, focus on being as structured as possible in every sentence you say and every answer you give ("ABS - always be structured"). For this, I wrote a distinct book with the most important frameworks and business concepts for case interviews (you can find it at This book not only gives you a short description and basic idea of the frameworks and concepts, but also a step-by-step guide on how to actually use and implement them (you would be surprised how many candidates don't have a clue about that!).
  • As soon as you master the case interview basics, start preparing the behavioural part of the interviews; this is especially important for McKinsey as this is the part where most candidates really fail. Recently I have added a blog with free expert advice on the McKinsey PEI where I am sharing some answers on the most common PEI questions that I receive from candidates (; I also wrote a distinct ebook for "The Ultimate McKinsey PEI Prep" (
  • If time permits, read some general books about consulting to get a good understanding how the industry works, like "The Firm" by Duff McDonald, "Managing the Professional Service Firm" by David Maister and "The McKinsey Way" by Ethan Rasiel

Hope that helps - if so, please give it a thumbs-up with the green upvote button below!


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replied on Jun 07, 2020
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School


I recommend the following approach:

1) Start with "Case in point" book - you can download this book for free everywhere. It's not the best guide on how you should approach the cases, however, it will give you the basic understanding.

2) Start practicing cases with partners here or find them locally. !!! Find experienced partners or coaches who can provide a good feedback!!!

3) Purchase and read Viktor Cheng Book (Amazon Kindle store) and listen to LOMS (his website). I recommend to reread the book and listen to LOMS every 15 cases. Every time, having more experience, you’ll be finding something new.

4) Practice fast math

  • Learn how to multiply double digit numbers (
  • Learn the division table up to 1/11 (i.e. 5/6 = 83.3)
  • Learn how to work with zeros (Hint: 4000000 = 4*10ˆ6)
  • Use math tools (Mimir math for iOS), Math tool on Viktor Cheng website to practice

5) Below you can find a list of the most common case types and some high-level recommendations on structuring:

  • Market sizing - structuring from the supply or demand side. Structuring using a formula or using an issue tree
  • Profitability - basic profitability framework. Remember about different revenue streams and product mix
  • Market context cases (Market Entry, New product, Acquisition, etc). Always start with the big picture "market". Finish with something specific to the case (e.g. How to enter?"). Structure it as if you are defining the work streams for the real project.
  • Operational math problem (e.g. Should we increase the speed of an elevator or just buy a second one? How should we reduce the queues? Etc.) - Structuring as a process / value chain, with inflows, operations, and outflows
  • Cost cutting - I provided the recommendations on structuring it here:
  • Valuation - Purely financial structure with cash flows, growth rate, WACC / hurdle rate, etc.
  • Synergies - revenue synergies (price, qty, mix) and cost synergies (value chain).
  • Social / economics cases (e.g. How to improve the quality of life in the city? How to increase the revenues of the museum?) - huge variability. Practice 3-5 social cases before the interview

6) Also, I would try to focus on the most common industries in the following priority(sorted by probability of getting a case): 1-retail and CPG; 2-airlines; 3-Telecom; 4-banking; 5-natural resources; 6-tech

7) ! Important: don't forget about the FIT interview part. Crafting you stories and backups stories will require a couple of weeks!


Here is a good list of articles regarding the different parts of the case:

1) Start with clarifying questions:

2) Communicating while structuring. Here is a long post by me on how to communicate the structure during the case study:

3) Using hypothesis. I made a post about hypothesis here:

4) Communicating while making calculations:

  • Always tell the interviewer your approach
  • Check with the interviewer that your approach is correct
  • Come to the interviewer with some preliminary answers
  • Check your assumptions with the interviewer

5) Communicating during the analysis of graphs / tables

  • Take a minute to look at the graph. Read the graph title. Look at the graph type and define the type (pie chart, line chart, etc). Look at the legend (ask for clarifying questions if necessary). Identify whats going on on the graph. Look for: Trends, % structures. Look for unusual things - correlations, outliers,
  • Make 3-4 conclusions from the graph. Think out loud on potential hypothesis on what could be the root cause / what are the consequences
  • Prioritize the most important for your current analysis and move forward with the case

6) Communicating while having questions on creativity

  • Ask an interview for a minute to think
  • Think of several buckets of ideas (e.g. organic growth / non-organic growth / differentiation). Remember to think as big as possible
  • Narrow down to each bucket and generate as many ideas as possible
  • Present the structure (buckets) and then your ideas

7) Communicating your conclusion. You can find a good example I've posted here:

8) Communicating your FIT stories

Use the top-down approach while communicating your stories. "The Pyramid Principle" is the must-read by ex McKinsey on this topic.

I recommend using the STAR framework:

  • In Situation, you should briefly provide the context, usually in 1 or 2 sentences
  • Task usually includes 2 or 3 sentences describing the problem and your objective.
  • Then you provide a list of specific actions you took to achieve the goal. It should take 1 or 2 sentences per action (Usually 3-4 actions). Note that the interviewer can stop you any minute and ask for more details.
  • The results part should have 1 or 2 sentences describing the outcomes. This part is finalizing your story - make sure it can impress the interviewer and stay in the memory.


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Anonymous updated the answer on Jun 07, 2020


Quick tips on interviews preparation:

  • Step 1 | Work on frameworks in books (e.g. case in point); amass content and build your tool box. Attention, the day of the interview in most cases you should not make a mapping between the frameworks you studied and the case stated by the interviewer. You often have to build a customized framework.
  • Step 2 | Train with peers. In a case study we test the structure of course, but also the business sense and the ability to use the indices or the data communicated by the interviewer. It is not a 1-way talk but a real discussion between two people. Here is the real limit of training using books.
  • Step 3 | Test yourself with people who have really been interviewer in consulting firms to benefit from cases that have been tested for real and feedback through the evaluation grids of consulting firms. Of course, I would be delighted to discuss it with you when will be in this phase of your preparation.
  • Step 4 | Multiply the applications and therefore the real interviews. Nothing prepares better than a case study in a real situation. Morever, the more applications you submit, the more you maximize your chances of having one or more offers. I recommend on the other hand, to start with the firms that you target less and to keep top priorities for later.

You find attached a slide I have made on this topic.

I finish by reminding that it's compulsory not to neglect the fit which is often less prepared than the case study. So please do not forget that this part of the interview counts as much as the case study, so it is very important not to improvise.

Case Interview Preparation Steps

Hope it helps



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Anonymous replied on Jun 06, 2020

Dear A,

I would recommend you the following algorithm:

1. Start learning and practicing the cases. Some you can find in Case Library and practice it with your partner or experience coach.

2. Purchase and read Viktor Cheng Book (Amazon Kindle store) and listen to LOMS

Once you feel you are not improving anymore, I would recommend you to take an expert coach for structured feedback and polishing your own performance.

Hope this helps



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replied on Jun 06, 2020
3+ years McKinsey consulting experience|Strategy @ Coursera |Oxford MBA


The books you mention are pretty good starting points (also watch Victor Cheng's YouTube & LOMS videos), but I would not stick to books for too long. Once you are familiar with the basic frameworks and concepts, I'd suggest you focus most of your time on 1-on-1 case practice (and revise additional concepts as you encounter them during case practice, e.g., discounting cash flows.)



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Content Creator
replied on Jun 08, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut


To add on top on what´s been shared, and particularly for the FIT part, the "Integrated FIT guide for MBB" has been recently published in PrepLounge´s shop (

It provides an end-to-end preparation for all three MBB interviews, tackling each firms particularities and combining key concepts review and a hands-on methodology. Following the book, the candidate will prepare his/her stories by practicing with over 50 real questions and leveraging special frameworks and worksheets that guide step-by-step, developed by the author and her experience as a Master in Management professor and coach. Finally, as further guidance, the guide encompasses over 20 examples from real candidates.

Feel free to PM me for disccount codes, since we still have some left from the launch!

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Anonymous replied on Jun 06, 2020

Hi there,

Indeed, these books will teach you the ABC's of case solving - what you need to do is to reach out to the preplounge community and/or friends to start giving you cases in an interview format.

Reading case books material is only 25% of the preparation - only when you sit on one end of the table and try to structure/communicate/solve a case given to you by an interviewer, you are able to reach 100%.

Feel free to reach out for additional specific tips



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Content Creator
updated an answer on Jun 06, 2020
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate
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Anonymous replied on Jun 06, 2020


Use books only to familiarize yourself with a case interview flow, frameworks and expected answer.

The most important however is many practices with a real partner because by doing that you can get used to the dynamic of a case interview.

Don't forget to practice mental math using one of the many online tools.

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Case replied on Jun 12, 2020

A great (and free) case prep resource that we would recommend is Case Dojo ( Case Dojo sends subscribers two original market sizing questions per week, with solutions hand-crafted by MBB consultants.

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Anonymous C replied on Jun 10, 2020

When you're not doing live cases with a partner, I recommend practicing market sizing. As you improve your market sizing skills, you will become more comfortable with uncertainty and more structured when breaking down problems, which will serve you well during case interviews.

There are free resources online like Case Dojo (, which sends out handcrafted market sizing problems and provide sample answers every Monday and Friday from MBB consultants.

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Robert gave the best answer


Content Creator
McKinsey offers w/o final round interviews - 100% risk-free - 10+ years MBB coaching experience - Multiple book author
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