The Complete Consulting Case Interview Prep Guide

What Is a Consulting Case Interview?

A case interview is a structured problem-solving exercise where an interviewer presents a business scenario and asks you to analyze it in real time. It is the core evaluation method at McKinsey, BCG, Bain (MBB), and virtually every other management consulting firm including Deloitte, Accenture Strategy, Oliver Wyman, and LEK.

Unlike finance interviews where you memorize technical answers, consulting cases test how you think, not what you know. The interviewer wants to see structured thinking, hypothesis-driven analysis, and clear communication.

The Four Types of Cases

1. Profitability Cases

The most common type. A company's profits are declining — figure out why and what to do.

Framework:

• Profits = Revenue - Costs
• Revenue = Price x Volume (break down by product, channel, geography)
• Costs = Fixed Costs + Variable Costs (break down by major categories)
• Isolate the driver, then propose solutions

Example: "Your client is a national restaurant chain. Profits have declined 15% over the past two years. What is going on?"

2. Market Entry Cases

A company wants to enter a new market — should they, and how?

Framework:

• Market attractiveness: Size, growth rate, trends, competitive landscape
• Competitive dynamics: Who are the major players? What are barriers to entry?
• Company capabilities: Does the client have the skills, assets, and brand to compete?
• Entry strategy: Organic build, acquisition, or partnership?
• Financial analysis: Expected revenue, costs, and time to profitability

3. Market Sizing (Estimation) Cases

Estimate the size of a market or quantity using logical assumptions.

Framework:

• Start with a known population or base number
• Apply segmentation and filters step by step
• State each assumption clearly
• Arrive at a reasonable estimate and sanity-check it

Example: "How many golf balls are sold in the United States each year?"

Start with the number of golfers (roughly 25 million), estimate rounds per year (15-20), balls lost per round (2-3), and you get a reasonable estimate of 750M - 1.5B golf balls per year.

4. M&A / Growth Strategy Cases

A company is considering an acquisition or needs to grow — evaluate the opportunity. For the finance side of M&A, see our merger model interview questions.

Framework:

• Strategic rationale: Revenue synergies, cost synergies, market access
• Target evaluation: Financial health, cultural fit, integration complexity
• Financial assessment: Valuation, ability to finance, expected ROI
• Risks: Integration challenges, regulatory issues, customer overlap

How to Structure Your Approach

Regardless of case type, follow this process:

1. Listen carefully and take notes — do not miss key details
2. Repeat back the question to confirm your understanding
3. Ask 2-3 clarifying questions before diving in
4. Lay out your framework — tell the interviewer the 3-4 areas you plan to explore
5. Work through each area systematically, asking for data when needed
6. Synthesize your findings into a clear recommendation

The Golden Rule

Be hypothesis-driven. Do not just explore randomly. State upfront: "My initial hypothesis is that the profit decline is driven by rising input costs on the cost side. Let me test that by looking at the cost structure first."

Quantitative Skills Matter

Many candidates focus only on frameworks and neglect the math. In most cases, you will need to:

• Calculate margins, growth rates, and break-even points
• Interpret charts and data tables quickly
• Do mental math accurately (practice this daily)

Top Mistakes in Case Interviews

• Forcing a memorized framework: Interviewers can tell immediately. Adapt your structure to the specific case
• Not asking clarifying questions: You will miss important context
• Going silent: Think out loud. The interviewer wants to see your reasoning process
• Jumping to conclusions: Do not recommend a solution before analyzing the data
• Ignoring the "so what?": Always tie your analysis back to a clear, actionable recommendation

Practice Strategy

The best case interviewers practice 30-50 cases before their interviews. Here is a suggested plan:

• Weeks 1-2: Learn frameworks and do 10 cases to build comfort
• Weeks 3-4: Practice with partners and focus on weak areas (math, synthesis)
• Weeks 5-6: Do timed mock interviews simulating real conditions

For more practice, see our consulting case interview questions guide. If you are also considering investment banking vs. consulting, IB Flash includes both consulting-specific case drills and finance interview content in our Question Bank, making it a useful tool if you are recruiting for both paths.