In This Article
What Is a Case Interview and Who Uses Them?
MBB Firms (McKinsey, BCG, Bain)
Big 4 Consulting (Deloitte, PwC, EY, KPMG)
Tech Strategy and Other Industries
Now that you understand the concepts, practice answering out loud.
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Types of Case Interviews You Will Encounter
Profitability Cases
Market Sizing Cases
Market Entry Cases
Mergers and Acquisitions Cases
Operations and Pricing Cases
Essential Frameworks for Case Interviews
The Profitability Framework
The 3C Framework (Company, Customers, Competitors)
Porter's Five Forces
The MECE Principle
Building Custom Frameworks
FRAMEWORK WARNING
Interviewers can instantly tell when a candidate is forcing a memorized framework onto a case. At McKinsey, BCG, and Bain, this is one of the fastest ways to get rejected. Use frameworks as inspiration for your structure, not as a script. The goal is to show that you can think, not that you can memorize.
Step-by-Step Approach to Solving Any Case
Step 1: Clarify the Problem (2-3 minutes)
Step 2: Structure Your Approach (2-3 minutes)
Step 3: Analyze Each Branch (15-20 minutes)
Step 4: Synthesize Your Findings (1-2 minutes)
Step 5: Recommend and Discuss Next Steps (2-3 minutes)
You have the knowledge.
Do you have the delivery?
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Sample Case Walkthrough: Full Solution
WHAT MADE THIS ANSWER STRONG
The candidate interpreted every data point rather than just collecting information. They did math proactively (turnover cost-benefit analysis) without being asked. They caught that revenue being nominally up but volume being down was an important nuance. They gave specific, quantified recommendations rather than vague advice. And they acknowledged risks and next steps. This is what a top-decile case performance looks like.
CASE: COFFEECO PROFITABILITY DECLINE
Prompt: Your client is CoffeeCo, a national chain of 500 coffee shops across the United States. Over the past 18 months, their operating profit has declined by $30 million, from $120 million to $90 million. The CEO has hired us to figure out what is going on and recommend a path forward. --- STEP 1: CLARIFY --- Candidate: 'Let me make sure I understand the situation. CoffeeCo operates 500 coffee shops nationally, and profits have fallen by $30 million over 18 months - a 25% decline. My objective is to diagnose the root cause and recommend actions to restore profitability. A few questions: Has the store count changed during this period? Are we looking at all locations or a specific region? And is there a target timeline for the turnaround?' Interviewer: 'Store count has stayed at 500. The problem is nationwide, not regional. The CEO wants a plan they can start implementing within the next quarter.' --- STEP 2: STRUCTURE --- Candidate: 'I would like to break this down into two main areas. First, Revenue - I want to understand if sales have declined, and if so, whether that is driven by fewer customers, lower spending per visit, or both. Second, Costs - I want to see if operating costs have increased, looking at both fixed costs like rent and labor and variable costs like coffee beans and supplies. I would like to start with revenue. Does this sound reasonable?' Interviewer: 'Good structure. Let us start with revenue.' --- STEP 3: ANALYZE --- Candidate: 'Can you tell me how total revenue has trended?' Interviewer: 'Revenue has actually increased slightly - from $800 million to $810 million.' Candidate: 'Interesting. So revenue is up by about 1%, but profits are down 25%. That tells me this is predominantly a cost problem, not a demand problem. That said, a 1% revenue increase might be below inflation, so there could be a real revenue issue masked by price increases. Let me confirm - have they raised prices recently?' Interviewer: 'Yes, they implemented a 5% price increase 12 months ago.' Candidate: 'So with a 5% price increase, we would expect revenue to be around $840 million if volume held steady, but we are at $810 million. That means volume has actually declined by about 3.5%. So we have two issues: volume erosion despite a price increase, and a cost problem. Let me shift to costs since that seems to be the bigger driver. Can you break down how costs have changed?' Interviewer: 'Here is the cost breakdown. Labor costs are up $20 million - from $320 million to $340 million. Coffee bean costs are up $15 million. Other costs are roughly flat.' Candidate: 'So $35 million in cost increases explains more than the entire $30 million profit decline - offset partially by the $10 million revenue increase. Let me dig into these. Starting with labor: $20 million across 500 stores is $40,000 per store. Is that driven by hiring more staff, higher wages, or both?' Interviewer: 'Primarily higher wages. They raised hourly pay by 15% to reduce turnover, which had been very high.' Candidate: 'Has the turnover investment paid off? What was turnover before and after the raise?' Interviewer: 'Turnover dropped from 120% annually to 80%.' Candidate: 'That is a meaningful improvement but still high. The $20 million in additional wages is significant. Let me do some quick math on whether the reduced turnover justifies the cost. If the average cost of hiring and training a new barista is roughly $3,000 to $5,000, and we have approximately 10,000 total employees across 500 stores, turnover going from 120% to 80% means we went from 12,000 to 8,000 departures per year - saving 4,000 hires. At $4,000 per hire, that is $16 million in savings. So the wage increase of $20 million is partially offset by $16 million in turnover savings - a net cost of only $4 million. The wage increase is actually a reasonable investment.' Candidate: 'Now let me look at the coffee bean cost increase of $15 million. Is this driven by higher prices per pound, higher volume of beans used, or a change in the bean mix?' Interviewer: 'Global coffee bean prices have increased by 20% due to supply disruptions in Brazil.' Candidate: 'So this is largely an external factor. $15 million on a base of roughly $75 million in bean costs - that checks out with a 20% increase. Let me think about what CoffeeCo can do about this. They have a few options: negotiate longer-term supply contracts to hedge against further increases, explore alternative sourcing regions, adjust the blend to use slightly less expensive bean varieties without noticeably affecting taste, or pass some of the cost through to customers via further price increases. Given that they already raised prices 5% and saw volume decline, I would be cautious about another price increase right now.' --- STEP 4: SYNTHESIZE --- Candidate: 'Let me pull this together. CoffeeCo is facing a profit decline of $30 million driven primarily by two cost increases: a $20 million labor cost increase from a 15% wage raise, and a $15 million increase in coffee bean costs from global supply disruptions. Revenue is nominally up but volume has declined about 3.5% following a 5% price increase, suggesting some price sensitivity. The wage increase is largely justified by turnover savings of approximately $16 million, making the net labor impact only $4 million. The bean cost increase is the bigger problem at $15 million.' --- STEP 5: RECOMMEND --- Candidate: 'I recommend three actions: First, address bean costs through supply chain optimization. Lock in 12-month forward contracts with multiple suppliers to reduce exposure to price volatility. Explore sourcing from Colombia and Vietnam as alternatives to Brazilian beans. This could save $5 to $8 million annually. Second, improve revenue per customer. Rather than raising base prices again, introduce premium offerings - specialty seasonal drinks and a loyalty subscription program. The goal is to increase average ticket size by 8 to 10% among existing customers without triggering further volume loss. Based on industry benchmarks, a well-executed loyalty program could generate an incremental $15 to $25 million in annual revenue. Third, optimize labor scheduling using demand forecasting. While the wage increase should stay, there is likely an opportunity to better match staffing levels to traffic patterns. Many coffee shops overstaffing during slow afternoon periods. Data-driven scheduling could reduce labor hours by 5 to 8% without cutting wages or affecting service, saving $10 to $15 million. The main risk is that the supply chain changes could affect coffee quality and brand perception. I would recommend piloting the blend changes in 20 to 30 stores before rolling out nationally. With more time, I would want to analyze the 3.5% volume decline more deeply to understand whether it is driven by the price increase, competitive dynamics, or changing consumer habits.'
Math Skills You Need for Case Interviews
Core Math Skills to Master
Mental Math Techniques
Practice Drills
The Fit and Behavioral Component of Consulting Interviews
What Consulting Firms Assess in Fit Interviews
The McKinsey Personal Experience Interview (PEI)
Common Fit Questions and How to Approach Them
Fit Interview Preparation Strategy
PEI DEPTH TEST
A good test for whether your story is PEI-ready: Can you answer 10 consecutive follow-up questions about it without repeating yourself or running out of detail? If not, you need a different story or you need to recall more details from the experience. McKinsey interviewers are trained to push until they hit the bottom of your story.
8-Week Case Interview Preparation Plan
Weeks 1-2: Build the Foundation
Weeks 3-4: Solo Case Practice
Weeks 5-6: Partner Practice
Weeks 7-8: Simulate and Refine
Resources for Each Stage
THE MOST COMMON PREPARATION MISTAKE
Candidates who practice 100 cases but never fix their fundamental approach do not improve. Doing 30 cases with focused feedback and deliberate improvement after each one will always beat doing 100 cases on autopilot. Quality of practice matters far more than quantity. After every practice case, write down two specific things you will do differently next time - and actually implement those changes.
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