Author: Taylor Warfield, Former Bain Manager and interviewer

Last Updated: March 31, 2026

 

Case interview format is the structure and style of the problem-solving interview that consulting firms use to evaluate candidates. Every major consulting firm, from McKinsey to Deloitte, uses some version of the case interview, and the format you face depends on the firm, the round, and sometimes even the individual interviewer.

 

There are four main case interview formats: candidate-led, interviewer-led, written, and group. In this guide, I will break down exactly how each format works, which firms use each one, and what you need to do to prepare for all of them.

 

But first, a quick heads up:

 

McKinsey, BCG, Bain, and other top firms accept less than 1% of applicants every year. If you want to triple your chances of landing interviews and 8x your chances of passing them, watch my free 40-minute training.

 

What Is the Format of a Case Interview?

 

A case interview is a 30 to 60 minute exercise where you and the interviewer work together to analyze a business problem and develop a recommendation. The interviewer presents a real or hypothetical business scenario, and you are expected to break it down, ask smart questions, crunch numbers, and deliver a clear answer.

 

Consulting firms use case interviews because they closely simulate the day-to-day work of a management consultant. According to McKinsey, BCG, and Bain recruiting materials, case interviews are the single best predictor of on-the-job performance. In my experience as a Bain interviewer, I found that how a candidate handles a case in 30 minutes tells you more than an hour of behavioral questions.

 

Most consulting firms conduct four to six case interviews across two rounds. First round interviews typically include two to three back-to-back interviews, each lasting 45 to 60 minutes. Final round interviews follow the same structure but are led by more senior partners. Based on publicly available data, roughly 30% to 40% of candidates pass the first round at top firms, and only 15% to 30% receive offers after the final round.

 

For a complete walkthrough of every step in a case interview, check out our case interview guide.

 

What Are the Four Types of Case Interview Formats?

 

There are four distinct case interview formats used across the consulting industry: candidate-led, interviewer-led, written, and group. The format you encounter depends on the firm, the office, the interview round, and even the personal preference of your interviewer.

 

Understanding the differences between these formats is critical because each one tests slightly different skills and requires a different preparation approach. For a broader look at the various types of business problems you might face, see our guide on case interview types.

 

What Is a Candidate-Led Case Interview?

 

A candidate-led case interview is a format where you drive the entire case from start to finish. The interviewer presents the business problem, and then you take the wheel. You decide which areas to explore, what questions to ask, and how to structure your analysis. The interviewer acts more like a client than a guide.

 

This is the most common case interview format. BCG, Bain, Deloitte, LEK, Oliver Wyman, and PwC all use candidate-led cases as their primary format. Roughly 70% to 80% of all case interviews across the industry follow this style.

 

The candidate-led format tests your ability to structure problems independently, form and test hypotheses, and lead a conversation to a clear recommendation. Having coached hundreds of candidates, I can tell you that the biggest differentiator in candidate-led cases is your framework. A strong, tailored framework sets you up for the entire case.

 

What Is an Interviewer-Led Case Interview?

 

An interviewer-led case interview is a format where the interviewer controls the direction and pace of the case. After you present your framework, the interviewer tells you which area to explore first and asks you a series of specific, pre-determined questions. You still need to think critically and show strong analytical skills, but you have less control over the case direction.

 

McKinsey is the most well-known firm for using interviewer-led cases. Their cases are developed by a central team and follow a specific script, especially in first-round interviews. Oliver Wyman, Strategy&, and Accenture also use interviewer-led formats in many of their offices.

 

Do not assume interviewer-led cases are easier. In my experience, they actually test deeper analytical skills because the interviewer can push you into specific, challenging quantitative problems. You may face complex math, detailed chart interpretation, or rapid-fire brainstorming questions. For a detailed comparison, see our article on interviewer-led vs. candidate-led case interviews.

 

What Is a Written Case Interview?

 

A written case interview is a format where you work independently with a packet of data and then present your findings. The interviewer gives you 20 to 40 pages of charts, graphs, tables, and text. They leave the room, and you have one to two hours to analyze the information, build presentation slides, and prepare a recommendation.

 

BCG and Bain are the most common firms to use written cases, but the specific format differs. At BCG, you typically receive about 40 slides, have 2 hours to prepare, and create your own presentation slides. At Bain, you receive 20 to 30 slides, have about 55 minutes, and handwrite your recommendations on pre-formatted slides. Neither format allows calculators in most offices.

 

Written cases are not used at every office or in every round. They appear most often in final round interviews. Always check with your recruiter so you know what to expect. For step-by-step preparation strategies, see our written case interview guide.

 

What Is a Group Case Interview?

 

A group case interview is a format where multiple candidates solve a business problem together and then present their solution to a panel of interviewers. Groups typically include three to six candidates. You are given the same case prompt and must collaborate to develop a recommendation within a set time limit, usually 30 to 45 minutes.

 

Group cases are the least common format at top consulting firms, but some offices still use them, particularly for junior roles. The key difference is that interviewers are watching your collaboration and leadership skills just as closely as your analytical ability. They want to see who drives the discussion forward, who listens well, and who helps the group reach consensus without dominating.

 

How Do the Four Case Interview Formats Compare?

 

The table below compares all four case interview formats side by side to help you quickly understand the key differences.

 

	Candidate-Led	Interviewer-Led	Written	Group
Who leads?	You drive the case	Interviewer guides	You work alone	Candidates collaborate
Key firms	BCG, Bain, Deloitte, LEK, Oliver Wyman	McKinsey, Strategy&, Accenture	BCG, Bain (select offices)	Varies by office
Duration	25 to 40 minutes	25 to 40 minutes	1 to 2 hours + presentation	30 to 45 minutes
Top skills tested	Structuring, leadership, hypothesis testing	Math, chart reading, analytical depth	Data analysis, presentation, time management	Collaboration, leadership, communication
Frequency	Most common (~70% of all cases)	Common at McKinsey	Uncommon, final round only	Rare

 

Which Firms Use Which Case Interview Format?

 

The format you face depends heavily on which firm you are interviewing with. Here is how the three most prestigious consulting firms handle their case interview process.

 

	McKinsey	BCG	Bain
Primary case style	Interviewer-led	Candidate-led	Shifting to interviewer-led
Interview rounds	2 rounds	2 rounds	2 rounds
Cases per round	2 to 3	2 to 3	2 to 3
Online assessment	Solve (game-based)	Casey chatbot	SOVA, TestGorilla, or online test
Written case?	No	Yes (some offices)	Yes (some offices)
Fit interview style	Personal Experience Interview (PEI)	Behavioral questions	Fit questions focused on teamwork

 

One important thing to know is that these are general tendencies, not hard rules. Partners in final round interviews frequently deviate from the standard format. A McKinsey partner might give a more open-ended, candidate-led case. A BCG interviewer might ask a series of structured questions. Always be prepared for both styles regardless of which firm you are interviewing with.

 

Other major firms follow similar patterns. Deloitte and PwC primarily use candidate-led cases. Kearney uses candidate-led cases with a strong quantitative emphasis and sometimes includes written cases. Accenture tends toward interviewer-led formats. For firm-specific details, see our BCG case interview prep guide.

 

What Is the Step-by-Step Flow of a Case Interview?

 

Regardless of whether your case is candidate-led or interviewer-led, every case interview follows the same general flow. Understanding this structure will help you stay calm and organized under pressure. Here are the six steps.

 

Step 1: Receive the case prompt and take notes. The interviewer will read a business scenario out loud. Write down the key facts, especially numbers, the client name, and the industry. According to former McKinsey interviewers, candidates who take organized notes perform significantly better overall.

 

Step 2: Synthesize and confirm the objective. Repeat the case back to the interviewer in your own words and confirm the core question. This takes about 15 to 30 seconds but prevents the most common case interview mistake: solving the wrong problem.

 

Step 3: Ask clarifying questions. Ask two to four targeted questions about things like the client's definition of success, specific product lines, or geographic scope. Do not ask more than four questions at this stage. You will have chances to ask more as the case unfolds.

 

Step 4: Build and present your framework. Ask for one to two minutes of silence, then create a structured framework with three to five categories that cover the major issues. Walk the interviewer through your framework, explaining why each area matters. For strategies on how to build strong frameworks, check out our case interview frameworks guide.

 

Step 5: Analyze the problem. This is the core of the case and takes up about 70% of the time. You will work through quantitative questions like market sizing and profitability calculations, and qualitative questions like brainstorming growth strategies or evaluating competitive dynamics. In candidate-led cases, you pick which areas to explore. In interviewer-led cases, the interviewer directs you.

 

Step 6: Deliver your recommendation. Clearly state your recommendation, give two to three supporting reasons backed by data from your analysis, and suggest next steps. The entire recommendation should take 60 to 90 seconds. Keep it crisp and confident.

 

What Skills Does a Case Interview Test?

 

Case interviews evaluate six core problem-solving skills. Interviewers use scorecards to rate your performance in each area, and your overall score determines whether you advance. According to recruiting data from top firms, most interviewers make their pass/fail decision within the first 15 minutes of a case.

 

Skill	What It Means	What Good Looks Like
Structuring	Breaking a problem into clear, logical parts	MECE framework tailored to the specific case, not a memorized template
Math	Performing calculations quickly and accurately	Clean mental math, structured approach, no calculator needed
Judgment	Drawing meaningful insights from data	Connecting numbers to the business question, not just stating facts
Creativity	Generating original, practical ideas	Structured brainstorming that goes beyond the obvious
Synthesis	Summarizing findings into a clear recommendation	Concise answer, supported by evidence, with clear next steps
Case leadership	Driving the conversation forward with confidence	Proactive, organized, and easy to follow throughout the case

 

If you want to master case interviews efficiently, my case interview course walks you through proven strategies for each of these six skills in as little as 7 days.

 

How Does the Case Interview Format Differ Between Rounds?

 

The format of the case interview stays the same between rounds, but the difficulty and stakes increase significantly. Understanding these differences will help you prepare for what is coming at each stage.

 

In first round interviews, your interviewers are typically Associates or Engagement Managers with two to four years of consulting experience. They tend to follow the case script more closely and are generally more predictable. Based on publicly available data from BCG, roughly 30% to 40% of candidates pass the first round.

 

In final round interviews, your interviewers are Partners with ten or more years of experience. Partners are more likely to deviate from the standard format. They may ask unexpected follow-up questions, challenge your assumptions more aggressively, or give a completely open-ended case that feels more like a real client conversation. Only about 15% to 30% of final round candidates receive an offer.

 

Some firms also add written cases or group cases exclusively in the final round. At BCG, for example, certain offices include a written case interview alongside the traditional cases. Bain has used written cases in offices across Asia. Always confirm the format with your recruiter before interview day so there are no surprises.

 

What Are the Newest Case Interview Formats?

 

The consulting industry has increasingly adopted digital and AI-driven case formats as screening tools before the live interview rounds. These newer formats do not replace traditional case interviews, but they add an extra hurdle early in the process.

 

BCG Casey chatbot. As of 2026, BCG uses an AI-powered chatbot called Casey as its primary online screening tool. The assessment lasts 25 to 30 minutes and includes multiple question types: multiple choice, short text answers, data interpretation, and a one-minute video recording of your final recommendation. You cannot pause or go back to previous questions.

 

McKinsey Solve. McKinsey uses a game-based assessment called the Solve (formerly the Problem Solving Game). This digital test measures your critical thinking and decision-making through interactive simulations rather than traditional case questions.

 

One-way video interviews. Some firms now use platforms like HireVue or SparkHire to administer one-way video fit interviews. You record your answers to pre-set questions, which are then reviewed by recruiters or AI. These are typically used for the behavioral portion of the interview, not the case itself.

 

Despite these digital additions, the core skills being tested remain the same. If you are well-prepared for traditional case interviews, you will be well-prepared for digital formats too. For more case interview examples to practice with, see our collection of 100+ case interview examples.

 

How Should You Prepare for Each Case Interview Format?

 

Your preparation strategy should be tailored to the specific format you will face. Here is how to prepare for each one.

 

For candidate-led cases: Practice driving cases from start to finish. Build custom frameworks for different case types, practice proposing which areas to explore, and get comfortable leading the conversation. The biggest mistake candidates make is being too passive. If you want a structured approach to building this skill, see our guide for case interview beginners.

 

For interviewer-led cases: Practice answering rapid-fire analytical questions independently. Focus on mental math speed, chart interpretation, and giving concise answers under time pressure. McKinsey interviewers in particular will move quickly from one question to the next, so you need to be able to switch gears fast.

 

For written cases: Practice analyzing large data packets under strict time limits. Build the habit of identifying the three to five most important insights from a stack of 30 or more slides, and practice creating clean, well-organized presentation slides by hand. Time management is the number one differentiator in written cases.

 

For group cases: Practice collaborative problem-solving with other candidates. Focus on active listening, building on others' ideas, and gently steering the group toward a structured approach. Interviewers are watching your interpersonal skills as much as your analytical ability.

 

Regardless of format, the foundation of case interview preparation is the same: learn the right strategies, practice consistently, and get feedback. Having coached thousands of candidates, I can tell you that the candidates who practice 15 to 20 full cases with a partner before their interviews are the ones who land offers.

 

Frequently Asked Questions

 

How Long Does a Case Interview Last?

 

A typical case interview lasts 25 to 40 minutes for the case portion. The full interview slot is usually 45 to 60 minutes, which includes 10 to 15 minutes of behavioral or fit questions before or after the case. Written case interviews are longer, typically lasting one to two hours for the independent work, plus 30 to 40 minutes for the presentation and discussion.

 

How Many Case Interviews Will I Have?

 

Most top consulting firms require four to six case interviews across two rounds. In the first round, you will typically have two to three interviews. In the final round, you will have another two to three interviews with more senior interviewers. You need to perform well in every single case to receive an offer.

 

Is McKinsey Interviewer-Led or Candidate-Led?

 

McKinsey primarily uses interviewer-led case interviews, especially in the first round. Their cases are centrally developed and follow a structured script. However, in final round interviews, McKinsey Partners sometimes deviate from the script and give more open-ended, candidate-led cases. Always prepare for both styles when interviewing with McKinsey.

 

Can I Use a Calculator in a Case Interview?

 

No. The vast majority of consulting firms do not allow calculators during case interviews. You are expected to perform all calculations mentally or on paper. Practicing mental math regularly is essential. Focus on multiplying and dividing large numbers, calculating percentages, and estimating quickly with round numbers.

 

What Happens If I Get Stuck During a Case Interview?

 

Getting stuck is normal and interviewers expect it. The best approach is to pause, verbalize what you know so far, and explain where you are stuck. Say something like, "Based on what we have found so far, I believe the issue is on the cost side, but I am not sure which specific cost driver to focus on next. Can you point me in the right direction?" Most interviewers will give you a hint. What matters is how you recover, not that you got stuck in the first place.

 

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