McKinsey Case Interview Questions: Patterns, Frameworks & 48-Hour Prep Plan

McKinsey case interviews are interviewer-led, hypothesis-driven, and structured around the McKinsey Problem Solving Test (PST) mindset. Unlike candidate-led cases at other firms, you'll be guided through specific questions—but you still need to demonstrate structured thinking at every step.

This guide covers the 5 most common McKinsey case patterns, the frameworks that actually work in interviewer-led formats, and a focused 48-hour prep plan.

TL;DR

• McKinsey cases are interviewer-led: you'll answer specific questions rather than driving the entire case structure.
• Focus on hypothesis-driven thinking: state your hypothesis, test it with data, refine or pivot.
• The 5 common patterns: profitability, market entry, M&A, pricing, and operations.
• Master math under pressure: McKinsey cases often include multi-step calculations.
• Use the 48-hour plan at the end to compress prep without sacrificing quality.

What McKinsey Actually Evaluates

The McKinsey Interview Format

Round Structure

First Round (2 interviews):

• Each interview: ~30 min case + ~10 min fit/PEI
• Cases are interviewer-led with specific questions
• Personal Experience Interview (PEI) focuses on leadership, influence, achievement

Final Round (3-4 interviews):

• Similar format but more senior interviewers
• Cases may be more complex or ambiguous
• Deeper PEI probing

Interviewer-Led vs Candidate-Led

McKinsey (Interviewer-Led):

• Interviewer asks specific questions
• You answer each question, then they guide to the next
• Less freedom to drive structure, more focus on each answer's quality

Other Firms (Candidate-Led):

• You propose the structure and drive the analysis
• Interviewer provides data when you ask
• More freedom but also more rope to hang yourself

The 5 Most Common McKinsey Case Patterns

1. Profitability Cases

Typical prompt: "Our client's profits have declined 20% over two years. What's going on?"

Structure:

• Profit = Revenue - Costs
• Revenue: Price (per unit, per customer) + Volume (customers × transactions × units)
• Costs: Variable (COGS, shipping, commissions) + Fixed (rent, salaries, overhead)

McKinsey twist: They'll often give you data and ask "What does this tell you?" rather than letting you request data.

Winning approach:

1. Acknowledge the structure briefly
2. When given data, interpret it immediately: "This shows volume is flat but price declined 15%, suggesting pricing is the primary driver"
3. Propose a hypothesis to test: "I'd hypothesize competitive pressure forced price cuts; let me check competitor pricing"

2. Market Entry Cases

Typical prompt: "Should our client enter the electric vehicle market in India?"

Structure:

• Market Attractiveness: Size and growth, Competitive intensity, Regulatory environment
• Company Fit: Capabilities match, Brand relevance, Cost position
• Economics: Investment required, Revenue potential, Payback period
• Risks: Execution risks, Market risks, Competitive response

McKinsey twist: They may ask you to size the market, then evaluate fit, then calculate economics—each as separate questions.

Winning approach:

1. For market sizing: Use clear top-down or bottom-up logic; show your math
2. For fit assessment: Be specific about which capabilities matter and why
3. For economics: Calculate break-even and payback; discuss sensitivity

3. M&A / Due Diligence Cases

Typical prompt: "A private equity firm is considering acquiring a regional hospital chain. Should they proceed?"

Structure:

• Standalone Value: Current financial performance, Market position, Growth trajectory
• Synergies: Revenue synergies (cross-sell, pricing power), Cost synergies (consolidation, procurement)
• Valuation: Comparable transactions, DCF considerations, Premium justification
• Risks: Integration complexity, Regulatory approval, Key person dependencies

McKinsey twist: Heavy emphasis on quantitative analysis—expect to calculate EBITDA multiples, synergy values, or return on investment.

4. Pricing Cases

Typical prompt: "Our client is launching a new SaaS product. How should they price it?"

Structure:

• Cost-Plus: Unit economics, Target margin
• Value-Based: Customer willingness to pay, Value delivered vs alternatives, Price sensitivity by segment
• Competitive: Competitor pricing, Differentiation premium/discount, Market positioning
• Implementation: Pricing model (subscription, usage, tiered), Discounting strategy, Price communication

McKinsey twist: They often combine pricing with market sizing or profitability—"If we price at X, what's the revenue impact?"

5. Operations / Process Improvement Cases

Typical prompt: "Our client's warehouse fulfillment costs are 30% above industry benchmark. How can we reduce them?"

Structure:

• Diagnose: Process mapping (where are the bottlenecks?), Benchmarking (where are we vs best practice?), Root cause analysis (why the gap?)
• Improve: Quick wins (low effort, high impact), Medium-term initiatives, Structural changes
• Implement: Prioritization (impact vs effort), Timeline and milestones, Change management

McKinsey twist: Expect specific questions like "What data would you need to identify the root cause?" or "How would you prioritize these initiatives?"

Math Patterns You Must Master

McKinsey cases are math-heavy. Practice these patterns until they're automatic:

Percentage Changes

• "Revenue grew from $80M to $92M" → ($92-$80)/$80 = 15% growth
• "Costs are 120% of last year" → 20% increase, not 120% increase

Weighted Averages

• "60% of customers pay $100, 40% pay $150" → 0.6×$100 + 0.4×$150 = $120 average

Break-Even Analysis

• Break-even units = Fixed Costs / (Price - Variable Cost per Unit)
• Break-even revenue = Fixed Costs / Contribution Margin %

Growth Calculations

• CAGR: If something doubles in 5 years, CAGR ≈ 15% (rule of 72: 72/5 ≈ 14.4%)
• Year-over-year: Be careful about base effects

Market Sizing

• Top-down: Population → Segment → Penetration → Spend
• Bottom-up: Units × Price × Frequency

The Personal Experience Interview (PEI)

McKinsey's PEI is as important as the case. They assess three dimensions:

Leadership

Prompt: "Tell me about a time you led a team through a difficult situation."

What they want: Evidence you can influence others, make tough calls, and drive results.

Structure your answer:

• Situation (brief context)
• Your specific leadership actions
• How you influenced/motivated others
• Quantified outcome

Personal Impact / Achievement

Prompt: "Tell me about your most significant professional achievement."

What they want: Evidence of high standards, initiative, and measurable impact.

Structure your answer:

• Why this was challenging
• What you specifically did (not your team)
• The measurable result
• Why it mattered

Overcoming Challenges

Prompt: "Tell me about a time you faced significant resistance or obstacles."

What they want: Resilience, problem-solving, and learning orientation.

Structure your answer:

• The obstacle and why it was significant
• Your approach to overcoming it
• What you learned
• How you've applied that learning since

48-Hour Prep Plan

Day 1 (AM) — Foundations (90 min)

Framework review (45 min):

• Write out structures for: Profitability, Market Entry, M&A, Pricing, Operations
• For each, list 3 "McKinsey-style" questions an interviewer might ask

Math warm-up (45 min):

• 10 percentage change problems
• 5 weighted average calculations
• 3 break-even analyses
• 2 market sizing estimates

Day 1 (PM) — Two Full Cases (120 min)

Case 1: Profitability (45 min)

• Find a McKinsey-style case online or use a case book
• Practice answering specific questions, not driving the whole case
• After: Write down 3 things you'd improve

Case 2: Market Entry (45 min)

• Include a market sizing component
• Practice hypothesis formation: "My hypothesis is... because... I'd test by..."
• After: Write down 3 things you'd improve

Review (30 min):

• What patterns did you notice?
• Where did your math slow down?
• How clear were your syntheses?

Day 2 (AM) — PEI Prep (60 min)

Story development:

• Write 3 PEI stories: Leadership, Achievement, Overcoming Challenge
• For each: 2-minute version and 30-second version
• Add specific numbers and outcomes to each

Practice delivery:

• Record yourself telling each story
• Check: Are you answering the question asked? Is it under 2 minutes?
• Refine based on recording

Day 2 (PM) — Mock Interview + Polish (90 min)

Full mock (45 min):

• Case (25 min) + PEI (15 min) + feedback (5 min)
• Ask a friend or use a practice partner platform
• Focus on: hypothesis clarity, math accuracy, synthesis quality

Final polish (45 min):

• Review weak areas from mock
• Re-do any math types you struggled with
• Prepare 3 questions to ask your interviewer
• Logistics: quiet space, pen and paper ready, water nearby

Common Pitfalls (and Fixes)

1. Not Answering the Question Asked

Problem: Interviewer asks "What does this data tell you?" and you launch into a framework. Fix: Answer the specific question first, then connect to broader structure.

2. Math Errors Under Pressure

Problem: Simple calculation mistakes that undermine credibility. Fix: Write out your math. Sanity-check results. "That's $50M, which is about 10% of revenue—that seems reasonable."

3. Weak Synthesis

Problem: Ending with "So there are several factors..." instead of a clear recommendation. Fix: Always end with: "Based on X, I recommend Y, with the key risk being Z."

4. Generic PEI Stories

Problem: Stories that could apply to anyone, with no specific details. Fix: Add numbers, names (if appropriate), and specific actions YOU took.

5. Not Adapting to Interviewer Cues

Problem: Continuing down a path when the interviewer is trying to redirect. Fix: Listen actively. If they interrupt or redirect, follow their lead.

Questions to Ask Your McKinsey Interviewer

• "What's been the most interesting problem you've worked on recently?"
• "How do teams at McKinsey typically collaborate across offices?"
• "What distinguishes consultants who progress quickly here?"
• "What's one thing you wish you'd known before joining?"

Printable Checklist

• 5 case frameworks written out (Profitability, Market Entry, M&A, Pricing, Ops)
• Math patterns practiced (%, weighted avg, break-even, sizing)
• 2 full cases completed with self-review
• 3 PEI stories prepared (Leadership, Achievement, Challenge)
• 1 mock interview completed
• 3 questions for interviewer ready
• Logistics confirmed (quiet space, materials, timing)

If You Remember One Thing

Hypothesis-driven thinking is the McKinsey signature. Don't just structure problems—form hypotheses, test them with data, and refine. Every answer should sound like: "My hypothesis is X because Y. The data suggests Z, which [confirms/challenges] my hypothesis. Therefore, I'd recommend..."

This approach demonstrates the structured, analytical thinking McKinsey values—and it's what separates candidates who get offers from those who don't.

Want a personalized McKinsey prep plan? SwiftPrep analyzes real interview data to create custom study plans focused on the case types and PEI themes you're most likely to face.