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How to start preparing for case interviews?

Bain BCG Mck New newbie
New answer on Feb 11, 2020
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Anonymous F asked on Feb 09, 2020

Hi all,

I highly appreciate the content on this site and have heard a lot of the qualified answers to detailed questions. Today, however, I have a very simple question I am just in the process of applying for consultancy firms: how do I start preparing effectively for case interviews?

There is a lot out there in the www and to be honest I am a little bit overwhelmed. For me it makes sense to get the basics right first, improve my math skills, getting to know case structures etc.

1.Do you have recommendations for books / case books I should read first?

2. Should I schedule an appointment with a certified Preplounge coach early on? 3. When would be the time, after I got my case basics right, to schedule preplounge interview trainings?

highly appreciate your help,



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Best answer
replied on Feb 09, 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 the 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.


Content Creator
replied on Feb 10, 2020
#1 Coach for Sessions (4.000+) | 1.500+ 5-Star Reviews | Proven Success (➡ | Ex BCG | 10Y+ Coaching

Hi Anonymous,

please find my answers below:

1) I would recommend the following:

  1. Identify the companies interesting for you. Many people are interested mainly in MBB, you can start defining the exact list of companies interesting for you for the internship
  2. Define a calendar for your preparation. Check if there is any deadline for the internship applications. Then identify how many hours you have before that and allocate a time slot for preparation in your calendar for each day, working on the points below. Many people need 100+ hours to be ready before the interview so you can keep that as a benchmark
  3. Read Case In Point or Case Interview Secrets for a general understanding of what a consulting interview is. Don’t focus on the structures proposed in the books though, as they are not good enough nowadays.
  4. Start reading good MBA Consulting Handbooks – you can find several for free online (Insead is a good one to start). Read the cases and try to apply your structure to solve them. Whenever you see there is something missing, upgrade your structure with the new insides. PrepLounge also has a Case Library that you can use. Try to read at least a new case per day – in this way you will absorb better the information with constant learning.
  5. After the first 5-10 cases in books/handbooks and basic theory, start to practice live. PrepLounge can be helpful to connect with other candidates for that. There is a relevant part of the interview score that is based on your communication, which you cannot practice at all if you read cases only. Keep track of your mistakes and see if you repeat them. If so, try to identify the source of the mistake (feedback of experienced partners would be particularly useful for this). Be sure to focus on both the behavioural part and the case part. The case part should also cover market sizing, mental math and graph analysis.
  6. Before your application, be sure to review your CV and Cover, so that they are in the required format for a consulting application
  7. At least three weeks before the application deadline, start networking to find referrals for your target companies. You can find some tips on how to do that here:
  8. Once you feel you are not improving anymore, if you have a tight time constraint or if you want a realistic assessment of your level, consider using support from experts to strengthen your performance
  9. Before the interview, be sure to prepare your questions for the interviewer –great way to show you prepared in advance and to connect with the interviewer for a good final impression.

2) If you want to save time, it is a good idea to book a coaching session early on. However, I would recommend to do or read at least 5 cases before booking a session.

3) If you mean P2P training with peers, you can start immediately. If you mean a coach, I would recommend that you have gone through at least 5 cases before booking a class.



Content Creator
replied on Feb 11, 2020
McKinsey | NASA | top 10 FT MBA professor for consulting interviews | 6+ years of coaching

Hi, I recommend starting with Cosentino's book to fix the theory, then suddenly go into mock cases with other strong candidates. After the first cases support with a coach or with a senior consultant (if you have friends in consulting) will boost your preparation. To reach a good level 40-50 mock cases are needed.


Content Creator
replied on Feb 10, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut


On top of all the great strategies laid out in the post, I would challenge you with one key question that can change the whole approach: how much time do you have?

With "unlimited" (i.e., no interview set already and/or plenty of time to prepare), you should follow the detailed strategies commented.

However, if you are under time pressure and you follow that strategy, you would most likely fail, since it´s too time consuming. If this was the case, I would recommend you to prep a tailored plan with a coach, which optimizes timings very much (on the other hand, is expensive, so you need to see the trade-off)

Hope it helps!



Anonymous replied on Feb 10, 2020

Hey J,

I agree with my colleagues.

The only point I want to emphasize on is get help early.

An experienced coach, who also used to work in recruiting and select other candidates can save you a lot of time and guide you through the tailored preparation process according to your needs, while your chances to get several offers significantly increase.

Good luck in getting your offers!



Content Creator
replied on Feb 10, 2020
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate


Honestly, it sounds like you're suffering from the common issue of information overload. Let me help:

1.Pick 1. The "Best" one is abitrary and person-specific. Pick 1 and don't let yourself wander too much at first. I like Wharton's layout (they cover every base in a logical/sequential way that's very friendly on the eye):

2. Yes. Scheudle 1 session ASAP w/ someone here. They'll get you on the right track. Even if you never schedule a 2nd session, this is incredibly valuable in directing your efforts. If you pick me, I can assure you I'll keep you focused/target on what matters, but ultimately pick whoever you think will suit your style of learning!

3. When you feel you have a light grasp/understanding, but are nervous to begin :)

Content Creator
replied on Feb 09, 2020
BCG |NASA | SDA Bocconi & Cattolica partner | GMAT expert 780/800 score | 200+ students coached


I recommend the following approach:

1) Start with "Case in point" book or Victor Cheng "Interview secrets" (one of them is enough). They will give you the basic understanding.

2) Start practicing cases with partners here or find them locally

3) Prepare the fit interview part. Crafting you stories and answers to fit questions is crucial

Working with a coach since the early stage of your preparation could help you in order to prepare an effective workplan and to understand what are the most important points to focus on.
Feel free to write me if you want to discuss further about how to start your preparation.

Hope it helps,

Vlad gave the best answer


McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School
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