MBB Case Interview Prep 2026: How to Prepare for All 3

What McKinsey, BCG and Bain publish, side by side

Each firm publishes a different amount and a different kind of thing.

The exercise itself carries three different names across the three career sites. McKinsey calls it the Problem-Solving Interview and records that the market calls it a case interview. BCG writes "case study interviews". Bain writes "case interview" and publishes the only full definition of the three, on its case interview page at bain.com: "A case interview is a structured conversation where you work through a real business problem, the kind our teams tackle every day." The same page draws a scope line: "Case interviews are used for consulting roles only."

Two structural facts follow from the table. Only one of the three enumerates its stages globally, which is BCG. And only one page in all three firms' material publishes how long an interview lasts, which is BCG Switzerland. Everything else in a candidate's timeline comes from the recruiter, by email or by phone.

McKinsey: two interviews and four practice cases

McKinsey publishes the order of its interviews and the name it uses for the case. Its interviewing page at mckinsey.com states: "For most client-facing roles, you will participate in a personal experience interview, followed by a problem-solving interview. Depending on the role, you may also have expertise interviews. Your recruiter will confirm your interview details in advance."

Case format. Four practice cases with a statement and a worked solution: Beautify, Diconsa, Electro-Light and Talbot Trucks. The page states that "These cases contain logic, thought processes, and suggested answers." That is the largest case library of the three.

Rounds. No count published, and no duration. The recruiter confirms the details in advance.

Screening. Solve, which the firm describes as "a gamified assessment that tests your natural problem-solving abilities", and adds "There's no need to prepare." The length sits in the invitation email rather than on the page. McKinsey does name two Solve tasks on camera, in the English captions of its own introduction video, and our McKinsey Solve game page quotes that video task by task.

What changes in your prep. The behavioral half carries the countable requirement here. McKinsey publishes four themes, each with a definition and one question, and instructs candidates to bring "two personal examples that demonstrate how you've made an impact in each of the four areas below". Four themes at two examples each is eight stories, written before the interview rather than recalled during it. No other firm of the three publishes a quantity like that.

BCG: four stages and one published interview clock

BCG's global process page at careers.bcg.com names four stages: Application, Skills Interview, Case Interview, Team Interview. It describes the Skills Interview as exploring "your experience, skills, and motivation for joining BCG", and says the case interview assesses problem-solving and analytical skills for client-facing roles.

Case format. BCG hosts no case library on its own site. Its preparation page announces OneDay@BCG, a free job simulation of thirteen modules written by the firm and served by a third-party platform. The strategy module is a complete case in seven tasks, with model answers and corrected multiple-choice questions. The virtual experience page states "No grades · No assessments", and it forbids candidates to list the simulation as employment, work experience or an internship. The firm never calls those modules interview cases.

Rounds. The one published count is Swiss. BCG's Swiss page states: "Our interview process for full-time consulting roles begins with a virtual cognitive test, followed by one virtual first-round case interview and a final round of three in-person case interviews." Four cases in total, one virtual and three in Zurich. The cognitive test runs 30 minutes, and "The majority of questions will be in multiple-choice format and must be answered without any tools or resources." The first-round case runs 45 minutes and holds both halves: "First, we'll get to know what drives you. Then, you'll crack a client case." The same page warns that "Based on our overall impression from the first round, a decision may already be made at that stage", and states that the process differs between a full-time consulting role and a Visiting Associate internship. Those figures are Swiss and role-specific.

Screening. On the US Associate page, the Consulting Career Assessment arrives 30 to 90 minutes after you submit, runs about 30 to 35 minutes, and must be completed within 48 hours. A smaller group is then invited to an online case of about 35 minutes, roughly two weeks after the application deadline.

What changes in your prep. BCG publishes twelve named behaviors, six to do and six to avoid, which is the nearest thing to a checklist any of the three offers. To do: Listen Actively, Be Yourself, Think Structurally, Communicate Clearly, Clarify Assumptions, Show Your Thinking. To avoid: Panic Under Pressure, Rush Your Response, Overcomplicate Solutions, Ignore Feedback, Stay Silent, Interrupt. The same page states that "there isn't always a single 'right' answer".

Bain: two possible screens, then several rounds

Bain publishes the clearest definition and the least structure. Its case interview page gives the definition quoted above, and restricts the exercise to consulting roles.

Case format. Two practice cases, Coffee Shop Co. and FashionCo., each built in two tiers: a good answer, then a better answer on the same question. The gap between the two tiers is consistent across both cases, and it sits in four places: risk, alternatives, horizon, next step.

Rounds. "Several rounds", with no number and no duration. Bain's hiring process page adds the only reference to a scoring system among the three, saying feedback rests on "an objective scoring system" and that "After each interview, you'll learn exactly how it went."

Screening. A fork rather than a single test, published at bain.com: "you will receive an email after submitting the application detailing whether you are required to complete Sova or Test Gorilla". Both run about 30 to 40 minutes, and their rules differ. Test Gorilla: "Complete the test in one sitting". Sova: "You do not need to complete the Sova assessment in one sitting, but please ensure all sections are completed ahead of the deadline". Treating the two as interchangeable costs a candidacy, since one of them cannot be paused. Two further published rules: a calculator is allowed at this stage and ruled out in the interviews that follow, and "The use of AI tools are strictly prohibited".

What changes in your prep. The two-tier structure is a grading instrument, and it works on your own answers. Write your recommendation, then check it for risk, alternatives, horizon and next step. Those four are exactly what Bain's better answers add to its good answers.

MBB case interview prep rests on six published cases

McKinsey publishes four practice cases. Bain publishes two. BCG publishes none on its own site. Four plus two plus zero is six, and that is the whole case library a candidate gets from the three firms directly.

Across the career sites counted on 5 October 2026, firms publish 43 readable cases: Accenture 21, Deloitte 10, Oliver Wyman 6, McKinsey 4, Bain 2. The addition, redone by hand: 21 + 10 + 6 + 4 + 2 = 43. So the three serve 6 of 43, which is 6 over 43, or 0.1395, that is 14.0 percent. The remaining 37 come from firms outside the three. The thirteen OneDay@BCG modules sit on a separate line and stay out of that total, because the firm does not serve them and does not call them interview cases.

The practical consequence is straightforward. A candidate preparing for these three firms on their own material has six cases, which is a week of work at most. The other 37 are equally free, sit on other firms' career sites, and rehearse the same four shapes: a threshold, a profit movement, a sizing, an investment decision. A profitability case written by one firm trains the structure another firm will test.

Two of the six come first, for a specific reason. Bain's pair shows the distance between an adequate answer and a strong one on the same question, which is the only published example of that distance anywhere in the three. Read those two, name the four additions, then work the McKinsey four with the additions already in mind.

What none of the three publishes

Five absences, and each one matters for planning.

1. A weight or a marking scheme. None of the three publishes how a case answer is scored, or what counts for how much.
2. A pass threshold on any screening test or any case interview.
3. A round count, except on the one Swiss page.
4. An interview duration, except on that same page.
5. How the screening result weighs against the interviews. McKinsey states that Solve "will be considered in conjunction with the rest of your application and any other assessments you are asked to take", and stops there. Bain states that its assessment forms one part of the review.

One more absence is worth naming, because it is asserted everywhere. Nothing published by the three says how many candidates apply, how many are invited to interview, or what proportion receive an offer. No acceptance rate for McKinsey, BCG or Bain appears on any page of theirs. This site does not supply one.

What follows for a candidate is a planning rule. Build the calendar on the figures that exist, which are the screening windows and the Swiss clock, and treat everything else as confirmed by email. The 48-hour window on BCG's assessment is real and published. A "typical MBB timeline" of five rounds over eight weeks is not.

Splitting MBB case interview prep across three firms

The weights below are ours, read from the grading code in src/lib/grading. None of the three firms publishes anything comparable, and nothing here ranks them.

A six-week MBB case interview prep calendar

Six weeks, named by what each one produces. Start before you submit an application, because BCG's assessment can arrive within 90 minutes of applying and expires 48 hours later, and Bain tells you by email which of two tests you are taking.

1. Week 1, the published process. Read all three process pages, plus the country page for your office. The country page is where the numbers live. Write down the stages each firm names, and leave the gaps blank.
2. Week 2, the six cases. Bain's two first, then McKinsey's four. Time each one and write a one-page close before reading the suggested answer.
3. Week 3, the eight fit stories. Four McKinsey themes, two examples each. Tag every story twice, once with a McKinsey theme and once with a BCG competency, so one bank serves both firms.
4. Week 4, structure under the clock. Drill openings against 24 prompts, then grade three recorded answers against BCG's twelve behaviors, six to do and six to avoid.
5. Week 5, arithmetic and charts. Work them at the published screening pace, 30 to 35 minutes a block, with no calculator, since the interviews rule one out even where the digital assessment allows it.
6. Week 6, two full rehearsals. One 45-minute slot holding fit and case together, which is the published Swiss shape. Then four cases in one sitting, once, which is the published total for a Swiss consulting application.

Then move outward to the other 37 published cases, for volume on the same four shapes. For firm-by-firm detail, see the McKinsey case interview guide, the BCG case interview guide and the Bain case interview guide. For the prior decision, which form of practice to spend the hours in, the best platform to practice case interviews for MBB sets a peer, a coach, a written case, a scoring tool and the firms' own simulators against what each shape forbids. For the instruments themselves, McKinsey, Bain and BCG prep tools inventories what each firm hosts, where it hosts it, and the rules each publishes about what a candidate may use while preparing.