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Case Interview Preparation: A Complete Guide to Consulting Interviews

Case interviews are the defining hurdle between you and a career in management consulting. Unlike traditional interviews that ask about your past, case interviews test how you think in real time - giving you a business problem and watching you solve it. The good news: case interviews are highly learnable. With the right frameworks, consistent practice, and structured preparation, you can crack even the toughest cases at McKinsey, BCG, and Bain. This guide covers everything you need - from fundamental frameworks to a full sample case walkthrough to an 8-week preparation timeline.

What Is a Case Interview and Who Uses Them?

A case interview is a structured problem-solving exercise where an interviewer presents you with a real-world business scenario and evaluates how you break it down, analyze it, and arrive at a recommendation. Unlike behavioral interviews that probe your past experience, case interviews assess your analytical thinking, business judgment, and communication skills in real time. The format typically lasts 30 to 45 minutes. The interviewer describes a situation - for example, a retail chain experiencing declining profits - and you must work through the problem by asking clarifying questions, building a logical structure, performing calculations, and delivering a clear recommendation. There is rarely one correct answer. Interviewers care far more about your process than your conclusion. Case interviews originated at McKinsey in the 1950s and have since become the standard for evaluating consulting candidates worldwide. Today, they are used by a much broader set of employers than most candidates realize.

MBB Firms (McKinsey, BCG, Bain)

The Big Three management consulting firms are the most rigorous case interviewers. McKinsey uses a proprietary interviewer-led format where the interviewer guides you through specific questions within the case. BCG and Bain typically use a candidate-led format where you drive the structure and analysis direction. All three firms give two to three case interviews per round, with two rounds being standard. Expect four to six total cases before receiving an offer.

Big 4 Consulting (Deloitte, PwC, EY, KPMG)

The Big 4 accounting firms have rapidly expanded their consulting practices and now use case interviews for strategy and advisory roles. Their cases tend to be somewhat less abstract than MBB cases, often grounded in industry-specific scenarios related to the practice you are applying to. Deloitte S&O (Strategy & Operations) cases are closest to MBB in difficulty. PwC Strategy& also uses rigorous case interviews for strategy roles.

Tech Strategy and Other Industries

Tech companies like Google, Apple, and Amazon use case-style interviews for strategy, operations, and business analyst roles. Private equity firms use case interviews to evaluate deal assessment skills. Corporate strategy teams at Fortune 500 companies frequently use abbreviated case formats. Even some non-profit organizations and government agencies have adopted case-style assessments for analytical roles. If you are applying to any role that requires structured problem-solving, expect some form of case interview.

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Types of Case Interviews You Will Encounter

While every case is unique in its specifics, nearly all consulting cases fall into a handful of recurring categories. Recognizing the type of case you are facing helps you choose the right framework and allocate your time effectively. Here are the five most common types, roughly in order of frequency.

Profitability Cases

The single most common case type, especially for first-round interviews. You are told that a company's profits have declined (or are not meeting targets) and must diagnose the cause and recommend a fix. Approach: Decompose profit into Revenue and Costs. Revenue breaks into Price times Quantity (or by product line, geography, customer segment). Costs break into Fixed and Variable. Systematically investigate each branch, asking for data to identify where the problem lies. Often the answer involves one or two specific drivers - for example, a key customer segment is churning, or raw material costs have spiked. Common trap: Jumping to solutions before diagnosing. Always understand the root cause first.

Market Sizing Cases

Market sizing cases (also called estimation questions) ask you to estimate a number: How many tennis balls are sold in the United States each year? What is the annual revenue of all coffee shops in London? These are common at McKinsey as standalone questions and at BCG and Bain as components within a larger case. Approach: Build a calculation tree from the top down. Start with a population or base number you know (for example, the U.S. population of 330 million), then apply logical segmentation and assumptions. Always state your assumptions explicitly and explain your reasoning. Round numbers aggressively to keep the math clean. What interviewers evaluate: Your ability to structure an ambiguous problem, the reasonableness of your assumptions, and your comfort with quick mental math.

Market Entry Cases

Should Company X enter Market Y? These cases test your ability to evaluate the attractiveness of a market and a company's ability to compete in it. Approach: Assess market attractiveness (size, growth rate, profitability, competitive intensity), then evaluate the company's right to win (capabilities, brand, distribution, cost position). Consider entry mode (organic build, acquisition, joint venture, licensing) and associated risks. Quantify the financial opportunity if possible. Common trap: Saying yes because the market is large without evaluating whether the client can actually compete. A $50 billion market is irrelevant if the client has no competitive advantage.

Mergers and Acquisitions Cases

Should Company A acquire Company B? These cases combine financial analysis with strategic thinking. They are more common in second-round interviews and at firms with strong M&A practices. Approach: Evaluate strategic rationale (why does this deal make sense?), standalone valuation of the target, synergies (revenue synergies and cost synergies), integration risks, and whether the purchase price is justified. Consider both financial returns and strategic fit. Key distinction: Revenue synergies (cross-selling, geographic expansion) are less certain than cost synergies (eliminating duplicate functions, consolidating procurement). Good candidates acknowledge this uncertainty.

Operations and Pricing Cases

Operations cases focus on improving efficiency, reducing costs, or optimizing a supply chain or process. Pricing cases ask you to set or adjust pricing for a product or service. Both require quantitative analysis and a structured approach. Operations approach: Map the current process, identify bottlenecks or inefficiencies, quantify the impact of each issue, and prioritize improvements by feasibility and impact. Pricing approach: Understand the company's objective (maximize revenue, maximize market share, signal premium positioning), analyze costs (to set a floor), assess customer willingness to pay, and evaluate competitor pricing. Consider price elasticity and segmentation opportunities.

Essential Frameworks for Case Interviews

Frameworks are the scaffolding you use to structure your thinking. They provide a starting point, not a paint-by-numbers solution. The best candidates adapt frameworks to the specific case rather than forcing every problem into a rigid template. That said, you need to have these core frameworks deeply internalized before you start practicing cases.

The Profitability Framework

This is the most fundamental framework and the one you will use most often. Profit = Revenue - Costs Revenue = Price x Quantity Costs = Fixed Costs + Variable Costs From here, you segment further based on the business. Revenue can be split by product line, customer segment, geography, or channel. Fixed costs include rent, salaries, and depreciation. Variable costs include raw materials, commissions, and shipping. When to use it: Any case involving declining profits, underperformance, or financial analysis. Also useful as a component of market entry and M&A cases. Pro tip: Do not just recite 'Revenue minus Costs' and call it a structure. Customize the branches to the specific business. A SaaS company's revenue tree (new customers x price per license + existing customers x renewal rate x price) looks very different from a retailer's (foot traffic x conversion rate x average basket size).

The 3C Framework (Company, Customers, Competitors)

The 3C framework provides a holistic view of a business situation by examining three perspectives. Company: What are the client's capabilities, resources, cost structure, and strategic position? What is unique about their value proposition? Customers: Who are they? What do they need? How do they make purchasing decisions? Are there distinct segments with different behaviors? How is demand changing? Competitors: Who are the main competitors? What is their market share? How do they compete (price, quality, brand, distribution)? Are there new entrants or substitutes threatening the market? When to use it: Market entry cases, competitive strategy cases, and any situation where you need to understand the competitive landscape. This framework pairs well with a profitability analysis.

Porter's Five Forces

Michael Porter's framework evaluates the structural attractiveness of an industry by examining five forces. 1. Threat of New Entrants: How easy is it for new competitors to enter? Consider barriers like capital requirements, economies of scale, brand loyalty, and regulatory hurdles. 2. Bargaining Power of Suppliers: Can suppliers raise prices or reduce quality? Fewer suppliers and more differentiated inputs mean higher supplier power. 3. Bargaining Power of Buyers: Can customers demand lower prices or higher quality? Large, concentrated buyers with many alternatives have high power. 4. Threat of Substitutes: Are there alternative products or services that could replace the client's offering? Consider both direct substitutes and indirect ones. 5. Competitive Rivalry: How intense is competition among existing players? Consider number of competitors, industry growth rate, and exit barriers. When to use it: Evaluating whether to enter an industry, assessing long-term profitability of a market, or analyzing competitive dynamics. This is especially useful for market entry and M&A cases.

The MECE Principle

MECE (Mutually Exclusive, Collectively Exhaustive) is not a framework itself but the organizing principle behind every good framework. MECE means your categories do not overlap (mutually exclusive) and together they cover everything relevant (collectively exhaustive). Example of MECE breakdown for revenue decline: - Price-driven decline (price decreased) vs. Volume-driven decline (fewer units sold) - These are mutually exclusive (a given dollar of lost revenue is caused by one or the other) and collectively exhaustive (all revenue loss must come from price, volume, or both) Example of non-MECE breakdown (common mistake): - 'Maybe it is a marketing problem, or a product quality issue, or a competition issue' - These categories overlap (a competition issue could manifest as a marketing problem) and may not be exhaustive Apply MECE at every level of your structure. If your first level is MECE, your second level within each branch should also be MECE. This discipline is what separates top candidates from average ones.

Building Custom Frameworks

The best candidates do not mechanically apply textbook frameworks. They build custom structures tailored to the specific case. Here is how: 1. Listen carefully to the case prompt. Identify the core question being asked. 2. Think about what categories of information you would need to answer that question. 3. Organize those categories into three to four MECE buckets. 4. Under each bucket, list two to three specific sub-questions you want to investigate. 5. Prioritize which bucket to explore first based on likely impact. For example, if a hospital chain wants to reduce patient wait times, a custom framework might be: - Demand side (patient volume, arrival patterns, appointment scheduling) - Supply side (staffing levels, room availability, equipment) - Process efficiency (check-in workflow, handoffs between departments, discharge process) - External factors (seasonality, competitor closures, regulatory requirements) This is more useful than forcing the problem into a generic profitability or 3C framework.

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

Regardless of the case type, there is a consistent process that top candidates follow. Mastering this process is more important than memorizing frameworks. Here are the five steps you should follow in every case interview.

Step 1: Clarify the Problem (2-3 minutes)

After the interviewer presents the case, take a moment to make sure you fully understand the problem before diving in. Repeat back the key facts: 'So our client is a mid-size grocery chain in the Midwest that has seen a 15% profit decline over the past two years, and they want to understand why and what to do about it.' Ask clarifying questions: - What is the specific objective? (Diagnose the problem? Recommend a solution? Both?) - What is the scope? (One division or the whole company? Domestic or global?) - Are there any constraints? (Budget, timeline, strategic priorities?) - How do we define success? (Return to previous profit levels? Exceed industry benchmarks?) This step demonstrates that you think before you act - a critical consulting skill. Never skip it, even if you think you understand the case perfectly.

Step 2: Structure Your Approach (2-3 minutes)

Ask for a moment to collect your thoughts. This is expected and appreciated. Take 60 to 90 seconds of silence to sketch out your framework on paper, then present it to the interviewer. Present your structure clearly: 'I would like to explore this problem across three dimensions. First, I want to understand the revenue side - whether the decline is driven by price, volume, or mix changes. Second, I want to look at the cost structure to see if costs have increased. Third, I want to examine external factors like competitive dynamics and market trends. I would like to start with revenue since the prompt mentioned sales have been soft. Does this structure make sense to you?' Key tips for this step: - Use three to four buckets maximum. More than four becomes unwieldy. - Make your structure MECE. - State which bucket you want to start with and why. - Invite the interviewer to redirect you. They may say, 'The cost side is fine, let us focus on revenue.' This is helpful guidance, not a criticism.

Step 3: Analyze Each Branch (15-20 minutes)

This is the core of the case and where most of your time will be spent. Work through your structure systematically, asking for data and interpreting it. Good habits during analysis: - Ask specific, hypothesis-driven questions: 'I suspect the volume decline might be concentrated in a specific product category. Could you tell me how sales have trended by product line?' This is far better than a generic 'Can you tell me about their products?' - Interpret every piece of data you receive: When the interviewer gives you a number, say what it means. 'So premium product sales are down 30% while budget products are flat. This suggests the issue is concentrated in the premium segment.' - Do the math out loud: Show your work. Round numbers to make calculations manageable. State your assumptions. - Synthesize as you go: After finishing a branch, briefly summarize what you learned before moving to the next one. 'So on the revenue side, we have identified that the decline is driven by a 30% drop in premium product volume, likely due to a new competitor entering the premium segment last year. Let me now look at whether cost changes are compounding the issue.'

Step 4: Synthesize Your Findings (1-2 minutes)

Before giving your recommendation, take 15 to 30 seconds to organize your thoughts. Then deliver a clear synthesis. Use a top-down structure: - Lead with the answer (your recommendation) - Support with two to three key reasons - Acknowledge risks or next steps Example: 'Based on our analysis, I believe the profit decline is primarily driven by volume loss in the premium segment due to aggressive pricing by a new competitor. Revenue is down 15%, with premium products accounting for 80% of that decline. Costs have remained stable, so this is fundamentally a revenue problem.'

Step 5: Recommend and Discuss Next Steps (2-3 minutes)

Deliver a clear, actionable recommendation. Do not sit on the fence. Strong recommendation format: 'I recommend three actions. First, reposition the premium line by emphasizing quality differentiation and customer loyalty programs to stem the volume loss - this addresses the immediate problem. Second, explore launching a mid-tier product to capture price-sensitive customers who are switching to the competitor - this creates a new revenue stream. Third, conduct a detailed customer survey to understand exactly what is driving the switching behavior - this de-risks the first two actions with real data.' Always address risks: 'The main risk is that the premium repositioning may not be enough if customers have already formed loyalty to the competitor. I would want to pilot the loyalty program in two to three stores before rolling out nationally.' Mention what you would want to investigate with more time: 'If I had more time, I would want to understand the competitor's cost structure to assess whether their pricing is sustainable, and I would analyze customer lifetime value by segment to prioritize our response.'

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Sample Case Walkthrough: Full Solution

Let us walk through a complete case interview from start to finish. This is representative of a first-round case at BCG or Bain.

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

Case interview math is not advanced - you will never need calculus or statistics. But you do need to be fast, accurate, and comfortable performing arithmetic under pressure without a calculator. Many otherwise strong candidates fail cases because they freeze during the math portion or make errors that derail their analysis.

Core Math Skills to Master

Percentages: You must be able to calculate percentages instantly. Know that 15% of 800 is 120. Know that a change from 80 to 100 is a 25% increase. Practice until these are automatic. Growth rates: If revenue grows at 8% per year for 5 years, you should be able to estimate the result quickly using the Rule of 72 (doubling time = 72 divided by growth rate) or by compounding mentally. Break-even analysis: If fixed costs are $2 million and contribution margin per unit is $50, break-even is 40,000 units. You should be able to set up and solve these problems in under 30 seconds. Weighted averages: If Product A has 60% market share with 20% margins and Product B has 40% share with 10% margins, the blended margin is 0.6 times 20 plus 0.4 times 10 equals 16%. Unit economics: Revenue per customer, cost per acquisition, lifetime value, payback period. These come up constantly in tech and subscription-based cases.

Mental Math Techniques

Round aggressively: In a case interview, 4,872 times 312 should become 5,000 times 300 equals 1,500,000. Interviewers expect you to round and actually prefer it because it demonstrates business judgment about what level of precision matters. Break complex calculations into simpler ones: To calculate 15% of 840, calculate 10% (84) plus 5% (42) to get 126. Use benchmarks: Memorize key numbers. U.S. population is roughly 330 million. There are about 130 million households. Average household income is about $75,000. There are about 250 working days per year. These anchors speed up market sizing cases dramatically. Work in millions and billions: Write $3.2M instead of $3,200,000. This reduces errors and keeps your scratchwork clean. Always sanity-check your answer: If you calculate that the average American spends $50,000 per year on coffee, something went wrong. Build a habit of asking yourself whether the number makes real-world sense.

Practice Drills

Spend 15 minutes daily on mental math during your preparation period. Here are effective drills: Percentage chains: Start with 1,000. Increase by 20%. Decrease by 15%. Increase by 30%. What is the result? (Answer: 1,000 to 1,200 to 1,020 to 1,326) Market sizing speed rounds: Set a 3-minute timer and estimate: How many gas stations are in the United States? What is the annual revenue of the U.S. pet food market? How many flights take off from JFK airport daily? Profit calculations: Given revenue of $450M, COGS of 55%, SGA of 20%, and depreciation of $25M, calculate operating profit and operating margin as fast as you can. The goal is not to enjoy math. The goal is to make math so automatic that it does not consume mental bandwidth you need for the strategic thinking that actually wins the case.

The Fit and Behavioral Component of Consulting Interviews

Most candidates spend 90% of their preparation time on cases and 10% on fit questions. This is a mistake. At McKinsey, the Personal Experience Interview (PEI) carries equal weight to the case. At BCG and Bain, the fit portion takes up the first 10 to 15 minutes of every interview and directly influences your overall rating. Strong fit performance can tip a borderline case performance into an offer. Weak fit performance can eliminate a candidate who aced the case.

What Consulting Firms Assess in Fit Interviews

Firms are evaluating three things: Leadership: Can you motivate others, drive results, and take ownership? They want evidence that you have influenced outcomes, not just participated. Personal impact: Can you navigate conflict, handle ambiguity, and demonstrate resilience? Consulting is demanding - they need to know you will not crumble under pressure. Entrepreneurial drive: Have you gone beyond what was expected? Have you identified problems and solved them without being asked? Initiative and self-direction are essential in consulting.

The McKinsey Personal Experience Interview (PEI)

McKinsey's PEI is the most structured fit interview in consulting. Each interviewer picks one dimension - leadership, personal impact, or entrepreneurial drive - and spends 10 to 15 minutes drilling deep into a single story. They will probe relentlessly: What exactly did you do? Why did you choose that approach? What did the other person say? How did you feel? What would you do differently? You cannot survive a PEI with a surface-level story. Prepare three stories total - one for each dimension - and know each one cold. Each story should be: - Recent (within the last 2 to 3 years) - Specific (with names, numbers, and details you can recall under questioning) - Impactful (with measurable outcomes) - Revealing (showing genuine challenge, not a humble brag)

Common Fit Questions and How to Approach Them

Tell me about a time you led a team through a difficult challenge. Focus on your specific actions, not the team's collective work. What decisions did you make? How did you handle disagreements? What was the outcome, quantified? Describe a time you had to persuade someone who initially disagreed with you. Show that you listened first, understood their perspective, and used logic and evidence rather than authority to persuade. The best answers involve persuading someone senior to you. Tell me about a time you failed. Choose a genuine failure where you were responsible. Demonstrate self-awareness, specific lessons learned, and concrete evidence that you applied those lessons in subsequent situations. Why consulting? Why this firm? Be specific. Generic answers like 'I love problem-solving and working with smart people' are forgettable. Connect your answer to specific experiences, firm values, or conversations with consultants that shaped your interest.

Fit Interview Preparation Strategy

Build a story bank of 8 to 10 strong stories from your professional, academic, and extracurricular experience. For each story, write out the STAR format (Situation, Task, Action, Result) and practice telling it in 2 to 3 minutes. Then practice being interrogated. Have a friend or practice partner ask probing follow-up questions for each story. Where the story starts to feel thin - where you cannot remember details or your answers become vague - that is where you need to either strengthen the story or replace it. Record yourself answering fit questions and listen back. Most people are surprised by how many filler words they use, how often they say 'we' instead of 'I,' and how much they rush. Slow down, be specific, and own your contributions.

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

Structured preparation is the difference between candidates who get offers and candidates who do not. This 8-week plan assumes you are starting with basic business knowledge and can dedicate 10 to 15 hours per week to preparation. Adjust the timeline based on your starting point and target firms.

Weeks 1-2: Build the Foundation

Goal: Understand case interview formats and internalize core frameworks. Study core frameworks (Profitability, 3C, Porter's Five Forces, MECE) until you can explain each one without notes. Read 'Case in Point' by Marc Cosentino or 'Case Interview Secrets' by Victor Cheng to understand the format and expectations. Watch 10 to 15 recorded case interview videos on YouTube to see what good (and bad) performance looks like. Pay attention to how strong candidates structure their thinking, interpret data, and communicate. Start daily mental math practice - 15 minutes per day. Use apps or create your own drills. Begin drafting your fit stories. Identify 8 to 10 candidate stories and write each one out in STAR format. Do NOT practice live cases yet. You need the framework knowledge first, or you will build bad habits.

Weeks 3-4: Solo Case Practice

Goal: Apply frameworks to real cases independently. Work through 15 to 20 practice cases from casebooks (Harvard, Wharton, Kellogg casebooks are freely available online). For each case, practice the full process: read the prompt, build a structure, work through the analysis, and write out a recommendation. Time yourself. You should be able to outline a structure within 2 minutes and complete a full case within 30 minutes. Identify your weak spots. Are you struggling with math? Spend more time on drills. Is your structure always the same generic framework? Practice building custom frameworks for unusual industries. Refine your fit stories based on initial practice. Start practicing them out loud, not just in writing.

Weeks 5-6: Partner Practice

Goal: Simulate real interview conditions with a partner. Find two to three practice partners. Ideally, these are other people preparing for consulting interviews. If not, anyone who can read a case prompt and evaluate your communication will help. Do 3 to 4 practice cases per week with a partner, alternating between giving and receiving cases. Giving cases is almost as valuable as receiving them because it teaches you what interviewers look for. After each case, get detailed feedback on: Was your structure MECE? Did you interpret data or just collect it? Was your math accurate? Did you communicate clearly? Was your recommendation specific and supported? Practice fit interviews with partners as well. Have them probe your stories aggressively.

Weeks 7-8: Simulate and Refine

Goal: Peak performance through realistic simulation. Conduct full mock interviews: 15 minutes of fit plus 30 minutes of case, back to back, in a formal setting. Wear interview clothes. Use a desk or table. Treat it exactly like the real thing. Do 4 to 5 full mocks per week during these final two weeks. Your goal is to make the real interview feel routine, not novel. Focus on firm-specific preparation. McKinsey cases are interviewer-led with discrete questions - practice that format specifically. BCG and Bain cases are candidate-led - make sure you are comfortable driving the conversation. Review your most common mistakes from weeks 5 and 6 and drill those areas specifically. If you keep making arithmetic errors, do extra math practice. If your recommendations are vague, practice writing out strong recommendations. In the final three days before your interview, reduce practice volume. Do one light case per day maximum. Focus on rest, reviewing your fit stories, and building confidence. You have already done the hard work.

Resources for Each Stage

Books: 'Case in Point' by Marc Cosentino (framework fundamentals), 'Case Interview Secrets' by Victor Cheng (communication approach), 'Crack the Case System' by David Ohrvall (advanced techniques) Free casebooks: Search for MBA consulting club casebooks from Harvard Business School, Wharton, Kellogg, INSEAD, and LBS. These contain dozens of practice cases with solutions. Online platforms: Intervoo provides AI-powered case interview practice with real-time feedback. PrepLounge connects you with practice partners globally. CaseCoach offers video-based case training. Math practice: Victor Cheng's math drills (free PDF), mental math apps, or create custom spreadsheets that generate random calculation problems. Fit preparation: Record yourself answering fit questions using your phone or an AI practice tool. Listening to your own responses is one of the most effective ways to improve.

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.

Your Path to a Consulting Offer

Case interviews are challenging, but they are not mysterious. The format is well-documented, the frameworks are learnable, and the evaluation criteria are consistent across firms. What separates successful candidates is not raw intelligence - it is disciplined preparation and the willingness to practice deliberately, seek honest feedback, and continuously refine their approach. Start with the fundamentals: understand the case types, internalize the core frameworks, and sharpen your mental math. Then build toward realistic practice with partners and full mock interviews. Give equal attention to the fit component - it carries more weight than most candidates realize. Remember that interviewers are not trying to trick you. They are trying to simulate the experience of working with you on a real client engagement. Be structured, be curious, communicate clearly, and show genuine enthusiasm for problem-solving. If you follow the preparation plan in this guide and put in the hours, you will be ready to perform at your best when it counts.

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