What is a case interview?
A case interview is a structured conversation in which you work through a business problem with the interviewer. Bain's careers site calls it a conversation "where you work through a real business problem." BCG says you will be "presented with a realistic business challenge." Yale's career office says they are common in consulting and marketing hiring.
BCG's case interview preparation page lists the work you do inside one: "structure your approach, ask thoughtful questions, analyze data, perform quick calculations." You do all of that out loud, while the interviewer listens and hands you new facts. The case moves forward as a dialogue, so a silent candidate gives the interviewer nothing to assess.
At Bain, cases are limited to one track. Its case interview page says "Case interviews are used for consulting roles only." Other employers vary, so read the posting and ask the recruiter what each round includes.
What are interviewers looking for in a case interview?
They want to see how you reason. Bain says "We're not looking for a single right answer" and that it wants to see "how you think, structure problems, and build on ideas as the conversation evolves." BCG says "what matters most is how you approach the problem and the quality of your reasoning."
The final number matters less than the path to it. BCG names the traits it assesses: to "communicate clearly, think logically, and demonstrate both business intuition and creativity." Its page also gives a short list of do's and don'ts. The do's are listen actively, be yourself, think structurally, communicate clearly, clarify assumptions and show your thinking.
The don'ts are panic under pressure, rush your response, overcomplicate solutions, ignore feedback, stay silent and interrupt. Two of those, staying silent and ignoring feedback, are about the conversation itself. A hint from the interviewer is information, and using it well counts in your favour.
What types of case interview questions will you get?
Most beginner practice falls into three groups. Yale's Office of Career Strategy lists market sizing cases, strategy cases and quantitative questions or brain teasers. Strategy cases cover problems such as profitability, market entry, acquisition, organization and industry analysis. Each type tests a slightly different skill, so practice all three.
The table pairs each type with what Yale says it tests. The example prompts are made up for this page to show the shape of each case.
| Case type | What it tests, per Yale's career office | Example prompt (made up) |
|---|---|---|
| Market sizing | Thought process, structure, general business and numbers sense | How many cups of coffee are sold in Toronto on a weekday? |
| Profitability | Breaking a business problem into sub-problems, asking for and analyzing data | A regional grocery chain's profit fell for two years in a row. Why? |
| Market entry | The same strategy skills, applied to a growth decision | Should a US gym chain open locations in Canada? |
| Acquisition | The same strategy skills, applied to a deal | Should a bakery chain buy a smaller rival? |
| Quantitative question or brain teaser | How well you think on your feet | Estimate how long it would take to paint every house on one street. |
Yale adds that market sizing often has "a broad range of acceptable answers instead of one correct one." So an estimate that is far from a published figure can still score well. What the interviewer checks is whether each assumption makes sense and whether your arithmetic holds.
How do you structure a case interview answer?
Use the same five moves every time: confirm the question, lay out a structure, work through it out loud, check the numbers, and finish with a recommendation. Bain's tips cover the first two: "Clarify the objective" and "Use a clear framework and walk your interviewer through your approach." A routine keeps you calm when the case changes.
- Restate the question in one sentence and ask what success looks like. Bain says to "ask clarifying questions as needed."
- Take a short pause to write a structure, then walk the interviewer through it before you start solving.
- Work through the branches in order, saying what you are doing and why.
- Check every number against common sense before you move on.
- End with a clear answer, the two or three reasons for it, and what you would check next.
Here is an example opening for the grocery case in the table. It is made up for this page.
"So the goal is to find out why profit fell over two years and what to do about it. Before I start, is profit falling at every store or just some? And do we know if revenue or costs moved first? I'd like to split this into revenue and costs, then break revenue into number of customers and spend per visit."
Yale's tips say you don't need to memorize every framework, though you do need a structure. A structure built for this case beats a memorized one bent to fit. The STAR method guide works the same way for behavioral answers: a simple shape you fill with the facts in front of you.
How do you handle case math without freezing?
State your assumptions, round the numbers, and write every step down. Yale's career office says "Making assumptions during the case (and estimations) will help you solve the problem faster," and adds "Remember to always justify your assumptions." It also says to be scrupulous in your note taking. Clear notes let you and the interviewer catch an error early.
Here is a market sizing example with assumptions made up for this page. Say the city has 3 million people, and you assume half of adults drink coffee. Treat 80 percent of people as adults, which gives 1.2 million coffee drinkers. If each drinks 1.5 cups on a weekday and one cup in three is bought out, that is about 600,000 cups sold.
Say each of those steps out loud as you go. If the interviewer pushes back on one assumption, change that number and rerun the line. Nobody expects you to know the real figure, and Yale's note on a broad range of acceptable answers makes the same point.
Practice mental math in short daily sessions before the interview. Percentages, growth rates and multiplying large round numbers come up often. Keep pen and paper close, as Bain tells in-person candidates to bring them for "notes and case work."
How should a beginner practice case interviews?
Start with the firms' own practice cases, then move to live practice with a partner. Bain's case interview page offers two practice cases, Coffee Shop Co. and FashionCo., plus mock cases from RocketBlocks. Yale's career office says "The best preparation for case interviews is PRACTICE" and suggests 4 to 6 weeks of preparation.
A simple plan for 4 weeks might look like this. It is a suggestion built from the steps above.
- Week 1: read how a case works, do Bain's two practice cases alone, and practice mental math for 15 minutes a day.
- Week 2: do two live cases with a partner, one as candidate and one as interviewer, and write down where you got stuck.
- Week 3: do three or four live cases across market sizing, profitability and market entry.
- Week 4: do timed cases in the format your firm uses, and prepare your behavioral stories.
Playing the interviewer helps more than it seems. You see how a structure looks from the other side, and you notice when a candidate goes quiet for too long. BCG also offers OneDay@BCG, which it calls "a free job simulation that provides insights into the challenges we solve."
If your interview is on video, Bain's virtual tips apply. It says to test your internet, camera and microphone in advance, and to tell the interviewer when you are taking notes. The video interview tips guide covers the setup in more detail.
Do case interviews include behavioral questions?
Usually, yes. BCG's interview process page lists a skills interview before the case, described as a traditional interview that will "explore your experience, skills, and motivation for joining BCG." A BCG recruiting specialist quoted there warns that "it can be easy to forget that BCG interviews also include a behavioral portion." Prepare both.
Build four or five stories about leading a team, solving a hard problem, handling a setback and working with someone difficult. The behavioral interview story bank shows how to collect them. The guide to behavioral interview questions lists the common ones, and why should we hire you covers the motivation question most firms ask.
You can practice those behavioral answers in the Mock room. You answer out loud on a clock, get a score out of 10, and each answer is checked against your resume. It is included in the free plan.
What should you do after a case interview?
Write down what happened within the hour, while you still remember it. Note the case prompt, the structure you used, where you got stuck, any math errors and every hint the interviewer gave. Those notes show you what to practice before the next round, and they help if the firm asks you back for a final round.
The free debrief template gives you a page to fill in after each interview. The guide to preparing for round two covers what usually changes in later rounds, and the final round interview guide covers the last stage.