Case interview prep (6 steps to an offer at McKinsey, BCG, etc.)

Today we're going to explain how to prepare for case interviews, step-by-step.

We've helped more than 8,000 candidates get ready for their consulting interviews, and below we've summarised the six most important preparation steps you should take to help you land an offer. 

And here's one of the first things you'll want to know:

Memorising pre-made frameworks will NOT impress your interviewers. You need to learn to create custom frameworks that are tailored to the details of each individual case. We'll cover this in more detail in section 2.2 below. 

Now let's jump straight into step 1! 

1. Understand the 7 question types
2. Learn a repeatable method for solving cases
3. Solve practice cases (14 free example cases)
4. Prepare answers to fit and PEI questions
5. Practice answering questions out loud
6. Do 30+ mock interviews

Click here to practice with MBB ex-interviewers

1. Understand the 7 question types

We have analysed hundreds of case interviews over the past few years. And our conclusion is that case interviews are all made up of the same 7 types of questions:

The key to success is therefore clear:

If you learn how to consistently crack each type of question individually, then you will be able to consistently crack case interviews as a whole.

Now, in order for this to work, you’ll need to have a deeper understanding of what each question type looks like, so you can identify them.

To help with that, you can see examples of each question type in the below video:

2. Learn a repeatable method for solving cases

Understanding the question types is only the first step. 

You'll also need to learn how to solve each one consistently, and that's what we'll cover in this section. Let's jump straight in!

2.1  Situation

The objective of a case interview is for you to solve a business problem. So, during the first few minutes of the interview, your interviewers will lay out the situation of the company you're trying to help. 

You should always begin this part of the interview by summarising the situation back to your interviewers to ensure you’ve properly understood the most important details.

Then you can begin asking follow-up questions. 

In this example, you might want to ask follow-up questions like these: 

• How much have profits been declining?
• When did the decline begin? 
• What is the nature of the decline? Have they been declining at 1% per year for the past 5 years, or is it a recent and sudden 20% drop? 
• What’s the CEO’s objective? For example, is she aiming to just stop the profit decline or does she want to reverse the trend?

The answer to these questions will significantly influence how you solve the case. This part of the case interview aims to test your listening skills and whether you are taking the time to make sure you understand a problem before trying to solve it.

Now here is a summary of the steps you can take to consistently solve any situation question:

2.2  Framework development

Once the situation has been established, the second step is to develop a framework.  

In the car manufacturer example, your framework could have one branch on revenues and one branch on costs. By definition, profits will have gone down because of declining revenues, increasing costs, or both. And you need to look at both sides of the equation for your analysis to be comprehensive.

During a case interview, it often helps to literally draw your framework out on a piece of paper. This will help you organize your thoughts, and it will also help you explain your thinking to the interviewer, because you can simply show them the paper and walk them through the details. 

A common mistake a lot of candidates make is to memorise specific frameworks and to reuse them as-is in their interviews. Interviewers immediately spot and penalise candidates who do this because the objective of the framework question is to test your creativity and business acumen – not your ability to memorise frameworks!

As a result, you should focus your energy on learning to develop customised frameworks that address the information you gather in each case interview.

This might sound a little bit intimidating at first, but it becomes easy with practice. And creating good frameworks is one of the many things we teach in our case interview training programmes. 

Here’s an overview of the process you can use to solve any framework development question you encounter in your interviews:

2.3 Framework exploration

Once you’ve set up your framework, your interviewer will sometimes ask you to identify the root cause of the issue faced by your client. This is what we call the framework exploration question.

It’s worth mentioning that McKinsey usually doesn’t use this type of question, but it is sometimes used at other firms, like BCG, Bain, etc. 

This is one of a few differences between McKinsey’s “interviewer-led” approach and the “candidate-led” approach used at most other consultancies. To learn more about this distinction, check out section 2 of our McKinsey case interview guide.

The best method for identifying the root cause within a case is to explore your framework using a hypothesis-led approach.

For example, you might start by saying: “My initial hypothesis is that the profits issue faced by the company is driven by revenues.” You would then investigate the revenue side of your framework to identify if that’s where the root cause of the issue is. If revenues have been stable and are not the cause of the issue, you would then update your hypothesis and move on to the cost side.

For an example of this hypothesis-led approach, check out the BCG & Bain case extract we recorded previously: 

Since this method is focused on identifying the root cause, there wouldn’t be framework exploration questions in cases without an underlying issue. For example, it wouldn’t come up in market entry or new product launch cases. 

To summarise, here’s the repeatable process you can use for solving framework exploration questions:

2.4 Quantitative question – data provided

In each case interview, you will likely have to solve quantitative questions. The aim of these questions is to assess how comfortable you are solving problems with data. Broadly speaking, there are two types of quantitative questions.

The first is quant questions where you will be provided with data. This data usually comes in the form of graphs and tables or can also be provided by your interviewer orally.

This is the stage of case interviews where it becomes essential for you to be quick and accurate with mental maths. 

Basically every candidate will need a mathematics refresher prior to their interviews. Plus, there are some handy shortcuts you can learn to help you make calculations more easily. Check out our free case interview maths guide to learn more.  

Here’s the 4 steps that we recommend you take for each quantitative question you encounter:

2.5 Quantitative question - no data provided

The second type of quantitative question is where you are not provided with any data.  

This is the other type of question that isn’t typically used by McKinsey (this one and framework exploration), but other firms like BCG and Bain do ask this type of question.

The process for solving a quant question without any data is exactly the same as solving a quant question with data, except now you’ll be using the sub-step under step 2 below: 

If you’re not sure where to start with making data estimations, then we’d encourage you to study the process described in our market sizing question guide. 

2.6 Creativity question

At some point during your interview, you will also be tested on your creativity. This type of question is very open-ended. There are no right or wrong answers. 

Creativity questions aim to test your ability to generate new ideas and solutions, but you don’t want to do this in an unstructured way. 

Here’s the basic process for answering a creativity question systematically:

2.7 Recommendation

The last step of every case interview is the recommendation question. As the name suggests, this is the part of the interview where you’ll be asked to summarise your findings and to explain what the client should do.

For instance, you might recommend that your client solves their profit issue by launching new products that increase revenues. 

Regardless of what you recommend, there is a particular structure that you should use to deliver a thoughtful recommendation. Here it is: 

3. Solve practice cases (14 free example cases)

The best way to master the case interview process we've outlined above is to practice with realistic example cases. 

Below are several example cases for leading consultancies to get you started.

3.1 McKinsey case interview examples

• Beautify case interview (McKinsey website)
• Diconsa case interview (McKinsey website)
• Talbot Trucks case interview (McKinsey website)
• Shops Corporation case interview (McKinsey website)
• Conservation Forever case interview (McKinsey website)
• McKinsey case interview guide (by IGotAnOffer)
• McKinsey live case interview extract (by IGotAnOffer) - See below

3.2 BCG case interview examples

• Foods Inc and GenCo case samples (BCG website)
• Chateau Boomerang written case interview (BCG website)
• BCG case interview guide (by IGotAnOffer)
• Written cases guide (by IGotAnOffer)
• BCG live case interview extract (by IGotAnOffer) - See below

3.3 Bain case interview examples

• CoffeeCo practice case (Bain website)
• FashionCo practice case (Bain website)
• Associate Consultant mock interview video (Bain website)
• Consultant mock interview video (Bain website)
• Written case interview tips (Bain website)
• Bain case interview guide (by IGotAnOffer)
• Written cases guide (by IGotAnOffer)
• Bain live case interview extract (by IGotAnOffer) - See above

3.4 Other case interview examples

If your target firm isn't included above, or if you want even more practice cases, check out our list of 47 case interview examples. This list includes free cases for other firms like Deloitte, Accenture, Oliver Wyman, and PWC. There are several more McKinsey cases there as well. 

4. Prepare answers to fit and PEI questions

During case interviews, you'll typically be asked a few behavioural questions in addition to the case-related questions we covered above. So, in order for your overall case interview to be successful, you'll need to be prepared to answer behavioural questions. 

Behavioural interview questions can be categorised in two buckets:

• Fit questions. These are generic questions such as “Why consulting?” or “Why McKinsey / BCG / Bain?”
• Personal Experience Interview (PEI) questions. These are questions such as “Tell me about a time when you lead a team through a difficult situation,” or “Tell me about a time where you had to manage a team conflict” 

All firms ask a mix of these two types of questions, but some are more focused on one type than others. For instance, McKinsey almost exclusively asks personal experience interview questions. But Bain tends to put much more focus on typical fit questions such as “Why Bain?”

While case questions are used to assess your problem solving skills, fit and PEI questions are more focused on the three other attributes consulting firms look for: leadership abilities, entrepreneurial drive, and personal impact.

So what specific questions do you need to prepare for? We have analysed hundreds of interview questions on glassdoor.com for McKinsey, BCG, and Bain and have summarised the most common questions below. 

4.1 Top 5 fit questions (and how to answer them)

Let’s walk through the top 5 fit questions you will come across in your interviews and briefly discuss each of them.

Please note that the percentages listed below are of total fit questions. For instance, for 100 fit questions 26 will be “Why firm X?” As mentioned above, the balance between fit questions and PEI questions varies from firm to firm.

#1 Why firm X? (26% of fit questions)

If you've applied to BCG (for example), they'll want to know why you prefer their firm, and not McKinsey, Bain, or another company (even though you may have applied to them also!).

It's important to prepare an answer to this question that is totally unique to your target firm. This can be challenging if you don't think through it carefully, because many consultancies (especially MBB) have a lot in common. 

As a result, it's really useful to talk to consultants you've met about their firms, or to look at specific projects that your target firm has done. That will help you get more unique information that's not going to be the same across multiple firms. To learn more about preparing an answer for this type of question, visit our guides on the Why McKinsey / Why Bain / Why BCG questions.

#2 Why consulting? (24% of fit questions)

Consulting is an intense job. Consulting firms will therefore want to check that you have actually done your homework and that you have thought about why you want to be a consultant.

There are many great reasons to go into consulting. But here our three favourite ones:

• You will work for senior execs early in your career. This opportunity is unique. In most industry jobs you have to wait for many years to have the same level of exposure to CEOs / CFOs.
• You will learn a lot - very quickly. Changing industry and project every 3-6 months is one of the things that make the job challenging. But it also means your rate of learning will be much higher than in other industry jobs.
• You will work with bright people. Getting into consulting is hard and as a result your teammates will be extremely intelligent people. Consulting is one of the most stimulating environments you can be in.

#3 Introduce yourself / Walk me through your resume (14% of fit question)

This question is a great opportunity to summarise what you have done in the past in a way that illustrates how you would make a great consultant. For instance you could say something like:

“I’m Chris, I’m currently doing a master’s degree in economics at Cambridge. I think I’ve done three things in my studies / career so far that are relevant to consulting and motivated me to apply for this job. First, etc. ”

And you could then summarise the three most relevant points on your resume.

#4 Tell me something that’s not on your resume (6% of fit questions)

This question is particularly popular at Bain, and it helps your interviewers get to know you on a more personal level. They are trying to find out what kind of fun stuff you do outside of work. It could literally be anything: playing sports, being part of band, writing a book, etc.

Exactly WHAT you do outside of work doesn't matter as much as HOW you do it. Your interviewer will be looking for signs that you are pursuing that activity with passion, drive, and intensity.

For instance, answering that you are part of the national Northern Irish team for an obscure board game will get you noticed and your interviewer will think: “Cool, that’s pretty unique.” Whereas if you just say you play basketball once or twice a month your interviewer will probably think: “Ok, that’s not unheard of.”

#5 Tell me about your greatest accomplishment (4% of fit questions)

Unless your interviewer specifies that it’s ok to talk about an accomplishment outside of work / university, you should stick to these two areas.

A great answer will focus on a recent achievement that’s relevant to the skills you need to be a good management consultant.

The best thing to do for this question is to reuse one of the stories you will be preparing for Personal Experience Interview questions, which we will cover later in this guide.

#6 Other (26% of fit questions)

Finally, there is a long list of other fit questions that consulting firms ask, but they're not as common as the ones we've covered above.

If you have time towards the end of your preparation, after you've prepared thoroughly for case questions and the most common fit/PEI questions, we suggest coming back to the following additional fit questions:

• What are your strengths / weaknesses? (3% of fit questions)
• Where do you see yourself in 5 years? (3% of fit questions)
• What do consultants do in your opinion? (2% of fit questions)
• Why do you want to work for this specific office? (2% of fit questions)

4.2 Top 5 PEI questions

Personal experience interview questions are different to fit questions because they are less generic. They aim at testing the SPECIFIC skills you need to be a good management consultant.

Here are the main five themes that you're likely to encounter in these personal experience interview questions:

#1 Leading others (23% of PEI questions)

E.g.: Tell me about a time you led a team through a difficult challenge

#2 Managing a team conflict / situation (22% of PEI questions)

E.g.: Tell me about a time you worked in a team and had to manage a conflict

#3 Managing a personal conflict (21% of PEI questions)

E.g.: Tell me about a time you had a disagreement with a colleague / your boss

#4 Influencing others (17% of PEI questions)

E.g.: Tell me about a time you changed the mind of a group of people / an individual

#5 Overcoming challenges (11% of PEI questions)

E.g.: Tell me about a challenge you had to push yourself hard to overcome

#6 Other (7%)

4.3 How to prepare PEI stories

People remember stories. On the day of your interview, your interviewer will see 6 to 8 other candidates, so you need to build memorable stories that will make you stand out.

There are multiple ways to tell a story, but we like to keep things relatively simple with the framework below:

• Situation: start by giving the necessary context
• Problem: outline the problem you / your team were facing
• Solution: explain the solution you came up with to solve the problem
• Impact: if possible, quantify the impact you had in solving the problem
• Lessons: conclude with any lessons you learned in the process

Using this framework as a guide, we recommend preparing  5 specific stories that you can use to answer PEI questions during your interviews. 

By using this story-driven approach, you can typically use your stories for multiple different types of questions, which will help you be ready regardless of the specific PEI questions you encounter. 

If you are preparing for McKinsey, we would also encourage you to read our article on McKinsey PEI questions. The same five themes we covered above are used by McKinsey, but in slightly different proportions. And we also share common mistakes to avoid in that article.

5. Practice answering questions out loud

Your answers to behavioural and case questions are important, but your interviewers will also be evaluating how you COMMUNICATE your answers. It's important to speak in a structured way and to avoid drifting off topic or spending too much time on each question. 

We recommend that you practice by interviewing yourself out loud. Play the role of both the candidate and the interviewer, asking the questions and answering them, just like you would in an interview. 

This may sound strange, but it will help you master the rhythm of case interviews. It will also help you to memorise the key details of your answers for behavioural questions, without any crutches (like notes, glancing at your resume, etc.). 

Do your best to replicate the conditions of a real case interview as much as you can. It might help to look in a mirror while you're giving your answers. You may even find it helpful to practice in the same clothes you intend to wear to your interview. 

As you go through this process, if you'd like a broader list of questions to practice with, you can check out our consulting interview questions article.

6. Do 30+ mock interviews

Practicing by yourself is critical, but we all have gaps that we won't be able to identify without a partner that can see our performance more objectively. 

As a result, we recommend that you do as many mock interviews as possible before your interviews. In fact, we've found that most successful consulting candidates do 30+ mock interviews to prepare. 

This probably sounds like a lot, and it is, but case interviews are a skill that is developed with experience. And there are two main ways you can get this experience before your interviews:

6.1 Do mock interviews with friends and family

First, you can practice case interviews with friends, colleagues, or family. 

These are great ways to catch communication mistakes, but at some point you'll probably notice that the feedback you are getting isn't helping that much anymore. 

Once you reach that stage, we recommend practicing with ex-interviewers from top consultancies.

6.2 Do mock interviews with ex-interviewers

If you know a consultant who has experience running interviews at a top consulting firm, that's fantastic. Practice with them as much as you can!

But for most of us, it's tough to find the right connections to make this happen. And it might also be difficult to practice multiple hours with that person unless you know them really well.

Here's the good news. We've already made the connections for you. We’ve created a coaching service where you can practice 1-on-1 with ex-interviewers from leading consulting firms like McKinsey, BCG, Bain, etc. Book your consulting mock interview in a few clicks.