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McKinsey OEP first round Interview

McKinsey case interview McKinsey first round Mckinsey operations
New answer on Feb 29, 2024
4 Answers
Gianmarco asked on Feb 28, 2024
Currently prepping for MBB

Hi everyone,

I have the first round interview coming up for the junior supply chain management consulting position (OEP) in Mckinsey. 

Does anyone know how much knowledge I am expected to have about supply chain management/operations topics and if I will be tested on it. Also do you know where I can find realistic Mckinsey type cases to practice on?

Thanks a lot!!

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Content Creator
updated an answer on Feb 29, 2024
Highest-rated McKinsey coach (ratings, offers, sessions) | 500+ offers | Author of The 1% & Consulting Career Secrets

Hi there,

In general, operations cases often focus on concepts such as

Capacity issues

  • Increase / decrease capacity or move capacity from a less profitable product to a more profitable product
  • Analysis of bottlenecks

Classic profitability issues

  • Profit = Revenue - Cost :-)

Optimization problems

  • Optimize utilization of production machines
  • Optimize product mix to max out profitability

Stock issues

  • Calculation of safety stock
  • Optimization of stock

Value chain issues

  • Break down the value chain in its constituent profits and figure out where the issue is

Regarding the latter, you should be able to map out a process in an operations case, especially when you are not familiar with a certain task or system of interactions. When laying out what constitutes a certain issue, you will be able to understand it by breaking it down into its constituent parts.

This helps you to think deeper about the issue. It can also help you to get 'unstuck' if you don’t understand the situation. In sum, problem or process mapping forces you to deconstruct the interactions and increases your odds to find the segment or area in which the issue is buried in.

For instance, you might want to investigate chronological sequences. Process mapping can be used to make a chain of interactions visible and see all parts involved that produce a certain outcome. You can use it when you look into temporal events or when you want to find out which part of the process is most crucial, etc.

As regards the McKinsey case aspect:

McKinsey cases are a bit different and I would definitely stick to what you have seen in your mock interview with the firm. For more details, have a read:

Let's break it down below as well:

1. The difference between a McKinsey case and a non-McKinsey case first and foremost lies in the interviewer-led format as you are aware. Every case you have in this case book can be asked from an interviewer-led perspective.

In the McKinsey interview you will have to answer three different questions types - broadly speaking:

  • Structuring
  • Exhibit Interpretation
  • Math

While in candidate-led cases, they should arise naturally when you drill down into your structure, in McKinsey interviews, the interviewer will bring them up in succession.

2. The second big difference lies in the nature of questions asked at McKinsey. At the core, McKinsey wants to see creative ideas communicated in a structured manner, the more exhaustive the better.

As a result, McKinsey cases will usually be very creative in nature and not something that can be solved by looking at industry frameworks or industry trends.

Be aware that frameworks were applicable in the 2000 years, the era of Victor Cheng and Case in Point. McK has long caught up on this and the cases you will get during the interviews are tailored in a way to test your creativity and ability to generate insights, not remember specific frameworks.

3. The third big difference is how to answer the questions in a McKinsey interview. Since the interviewer guides you from question to question, you need to be in the driver's seat for each question and treat each almost like a mini case in itself.

Your goal should be to come up with a tailored and creative answer that fits the question. The framework should - broadly speaking - follow these three characteristics:

  • Broad
  • Deep
  • Insightful

The firm wants to see exhaustive and creative approaches to specific problems, which more often than not do not fit into the classic case interview frameworks (or can be derived from industry drivers and trends) that were en vogue 10 years ago...

Again, this only applies if everything you say

  • adds value to the problem analysis
  • is MECE
  • is well qualified
  • includes a detailed discussion of your hypotheses at the end

As a result, you can spend several minutes, guiding the interviewer through your structure!

Now for Structure and Exhibit Interpretation, there is also no right or wrong answer. Some answers are better than others because they are

  • deep
  • broad
  • insightful
  • hypothesis-driven
  • follow a strong communication (MECE, top-down, signposted)

That being said, there is no 100% that you can reach or the one-and-only solution/ answer. It is important that your answers display the characteristics specified above and supported well with arguments.

As for Math questions, usually, there are answers which are correct (not always 100% the same since some candidates simplify or round differently - which is ok), and others that are wrong, either due to the

  • calculation approach
  • calculation itself

The difference in format and way of answering a question is the reason why I recommend preparing very differently for McK interviews vs. other consultancies.

Now that you know about

  • the different format
  • the different question types and case briefs
  • the ways to answer the questions

you can start using the cases you already have and approach them in a McKinsey-specific way. 

If you have any more questions, please feel free to reach out for some free guidance on how to come up with your own McKinsey-type cases on the spot.

Also, check out this answer I wrote on how the cases McKinsey posts online are comparable to the actual interviews:




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Content Creator
replied on Feb 28, 2024
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate

Hi Gianmarco,

Nice work getting the interview!

It just so happens they tell you this

Please make sure to always check job descriptions for a firm…it's like interviewing 101!

So, make sure you know how to solve any case (they can still throw whatever case they like at you). But, also make sure to familiarize yourself with supply chain/operations topics.


Remember for procurement/supply chain, first you need to ask objective. In general this will either be "Reducing Costs" or "Fixing/Optimizing Production"

Within Reducing Costs, this could be contract renegotiation, finding new supplies, locking in futures contracts, automating processes (replace labor), changing transport methods, etc.

Within Optimizing Production, this could be a lot of the same i.e. automating processes, finding new suppliers, changing transport methods

Generally, you'll want to segment the supply chain/procurement process to identify problems (i.e. where taking the longest or costing the most).

For Practice Cases Try The Following

1) Search on Operations here (already done):[]=8&sort=real-case-desc&page=1&perPage=20

2) Google and casebooks are your friend. For example ( to Accenture, Amex, AT Kearney, Deloitte, and LEK sections which specifically call out operations.

3) Send me a message and I can provide you with a few good ones and/or case you in them!

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Content Creator
replied on Feb 29, 2024
#1 rated MBB & McKinsey Coach


At McK, they usually separate the technical round from the regular interviewing round. 

Reach out to the interviewer to ask about it and how they will set up the process for you. 

In the technical round, yes, you need to have a deep understanding of the technical terms that reflect the level of seniority that you're applying for. 

The way it goes is not that you are in a Q&A where they ask you a technical term and you answer it, but that you need to present stories which exhibit your expertise / knowledge in that area. Then, they ask deep-dive questions on that topic. 

For storytelling, specifically, you might be interested in looking into this course I offer:


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replied on Feb 29, 2024
30% off in April 2024 | Bain | EY-Parthenon | Roland Berger | Market Sizing | DARDEN MBA

They expect you to know the basics and yes, you will be tested within the usual case interview method.

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Florian gave the best answer


Content Creator
Highest-rated McKinsey coach (ratings, offers, sessions) | 500+ offers | Author of The 1% & Consulting Career Secrets
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