The four practice cases on McKinsey's interviewing page come with suggested answers, cost nothing, and were written by the people who will score you. In my experience they are also the least-used item on a candidate's list. Ask a first-round candidate what they prepared with and you hear a prep company's name; the firm's own page comes up perhaps one time in five, my rough count from the interviewer's chair, not a survey.
Rank free case interview resources by who wrote them and what happens to the author if you get better. The firms want you to walk in knowing the format, because a confused candidate tells them nothing, so their free material is complete. A prep company's free tier exists to sell the paid one, so it is a sample by design. And nothing free, from anyone, contains the one input that moves a score: somebody other than you grading the rep.
By the end you will have an audit of what five firms publish as of today, a method for turning one static prompt into three scored reps, and a price list for the part free does not cover.
Read the publisher before you read the page
Free is four publishers with four reasons for giving material away, and the reason predicts quality better than the web design does.
| Publisher | Why it is free | What it does well | What it will not do |
|---|---|---|---|
| The firm's careers site | They want the interview to measure your thinking, not your surprise at the format | Prompts, model answers, and the firm's own words on what it looks for | Score you; nothing on the page listens back |
| Business-school consulting clubs (casebooks) | Students wrote them for each other; the PDFs leak out every year | Volume: 20 to 40 prompts and exhibits per book | Edit itself; frameworks date, and arithmetic errors survive for years |
| Prep companies' free tiers | A sample that sells the paid tier | An occasional clear explainer or a single sample case | Give you the part you need; that part is paid, by design |
| Your phone's voice recorder | Nobody wrote it; it is a recorder | Turn a silent rep into an audible one you can count | Judge you on its own; you supply the counts |
Notice what is missing from every row. Nothing free scores you. That is the category's definition, not a defect of any one resource, and most lists of free resources are lists of prompts, which were never the scarce input.
What the firms publish, audited
I opened each page on 2026-09-24. Firms move these around; treat the table as a snapshot and the links as the way in.
| Firm | On the page today | Answer key | Best used for |
|---|---|---|---|
| McKinsey | Four practice cases (Beautify, Diconsa, Electro-Light, Talbot Trucks) with "logic, thought processes, and suggested answers", previews of PEI questions, and a table of permitted AI use | Yes | Interviewer-led structure, PEI framing |
| BCG | A description of the case (there "isn't always a single right answer"), a do and don't list, an associate's video, and OneDay@BCG, a free job simulation | No worked case in the page text | What BCG says it scores |
| Bain | Practice cases with show-the-answer steps, such as Coffee Shop Co., which asks for one to two minutes of structuring before you speak | Yes, step by step, including a breakeven | Candidate-led cases, market sizing |
| Deloitte | An interactive case tool for entry-level consulting candidates, split by practice area, 15 to 20 minutes a case, untracked, plus a five-step approach | Yes, check-your-work after each question | Deloitte's more guided format |
| Oliver Wyman | A six-step case method (pinpoint the issue, break it down, pick an approach, analyze, use numbers, recommend) and practice samples | Varies by sample | OW's reasoning sequence |
McKinsey's page is unusually explicit about tools: "practicing interview questions" with AI is marked encouraged, and "generating real-time answers during an interview" is not allowed. It also says of Solve, its gamified assessment, that "there's no need to prepare." Take the first at face value, and the second knowing that nobody was ever marked down for having seen what a game looks like.
Bain's Coffee Shop Co. is the best free worked case I know, because it shows its arithmetic. Price £3, variable cost £1, £245,610 to open, and £163,740 a year to run, so 2Q equals 409,350 and breakeven is 204,675 cups. You can check every step. Bain's interviewing page also states the consulting sequence plainly: a digital assessment, then case interviews.
BCG's page has no worked case in the text I could read, but it lists the verbs: structure your approach, ask thoughtful questions, analyze data, perform quick calculations, identify the most important factors, communicate clearly. Every scoring sheet I have used maps onto them.
Deloitte's tips page says you are "not expected to provide the 'right' answer, but rather to clearly convey your logic and thought process," and its five steps end with "outline next steps and expected results." Most candidates stop at the recommendation; Deloitte tells you, in writing, that it wants the step after.
Oliver Wyman's page frames the interviewer as your client: "They want you to solve the problem, and can help you to do so." The most useful sentence a nervous candidate can read, and it is free.
Smaller firms publish too; Kearney's careers site has a "Crack the case" section with a worked promotion-planning example. Go in through each careers menu rather than a saved link, since these pages move quietly.
Casebooks: free prompts, unpaid editors
Every autumn a fresh set of consulting-club casebooks from the big MBA programs circulates as PDFs: the largest free source of prompts and exhibits there is, with two problems the firm pages do not have.
First, second-year students wrote them in a hurry and nobody edits them afterward. I have seen exhibits whose segments do not sum to the total, and model answers with the decimal in the wrong place. Second, the framework pages at the front are the most-read and least-useful section. They teach you to recite categories, and reciting categories is what an interviewer marks down.
Use them as prompt and exhibit libraries only. Cover the model answer, do the case aloud, and when your number disagrees with theirs, check theirs. Finding the error is a better rep than agreeing with the key.
The thing no free resource contains
A model answer is an answer key for the destination. The scoring sheet grades the route: whether the structure came before the data, whether the set-up was spoken before the arithmetic, whether the recommendation led the close. Nothing printed can see the route. Only a listener can, and a listener with a rubric is the whole cost of case prep.
So treat free as a constraint on money, and notice that the real budget is hours. The role you are practicing for pays a median of $101,860 a year for US management analysts (Bureau of Labor Statistics, May 2025), with about 94,100 openings projected a year over the decade. Against that, the money side of prep is small. The hours side is not, and each way of getting scored spends hours differently.
| Way to get a rep scored | Money | Your hours per scored full case | Whose rubric |
|---|---|---|---|
| Record yourself and count | $0 | About 1, including the scoring listen | Yours, written down before you start |
| Campus club or peer swap | $0 | About 2, counting scheduling and interviewing them back | Usually nobody's; bring a printed one |
| AI interviewer such as CoachNed | $0 for seven days, no card; then $120 for a recruiting season or $49 a month | About half an hour, debrief included | Seven fixed dimensions, every time |
| Private coach | $200 to $400 an hour is common, in my estimate | 1 | The coach's, which is the point |
The first two rows are genuinely free and useful on one condition: a rubric exists before the case starts. A peer session where both of you improvise feedback is not free; it costs two hours and returns "good energy." A trial that asks for a card is not free either; a free week has no card and a stated end date.
Ned's rule. Judge a free resource by who wrote it and what happens to them if you get better. The firm wants you good in the room; everyone else wants you back on the site. Read the firm's page first, and read it twice.
Worked example: one free prompt, three scored reps
Here is how to get scored reps out of a static case with nothing but a phone. The case is invented.
Kestrel Bikes runs 12 bicycle shops in one region. Revenue has been flat at $14.4 million for two years while profit fell from $1.1 million to $0.7 million. The owner asks whether to close her two weakest stores.
Rep one, structure. Read the prompt, sit silent for 90 seconds, then speak your structure for two minutes into the recorder. Count three things on playback: branches (three or four), a "because" tying each to the question, and a stated starting point. A good opening here does not accept the question as posed: "Before I evaluate closing two stores, I want to know whether two stores can explain a $400,000 profit decline. My branches are store-level economics, chain-wide cost creep, and margin mix." The sheet calls that business judgment.
Rep two, math. Each weak store sells $800,000 at a 35 percent gross margin; its costs are $110,000 rent, $150,000 staff, and $30,000 other. If a store closes, 25 percent of its sales move to the nearest Kestrel shop and are absorbed by existing staff. Breaking a lease costs six months' rent.
Speak the set-up before any number: "Contribution is gross profit minus store costs. The closure gain is the loss I stop making, plus the gross profit I keep on transferred sales, minus the exit cost." Then the arithmetic. Gross profit per weak store is 0.35 times 800,000, or 280,000, against 290,000 of costs, so each loses 10,000 a year and the pair loses 20,000. Transferred sales are 200,000 per store, worth 70,000 of gross profit each, so 140,000. Lease exits cost 55,000 each, 110,000 once. Year one: 20,000 plus 140,000 minus 110,000, or 50,000. Every year after: 160,000.
Now the sentence the interviewer is waiting for. "Closing both stores adds about $160,000 a year from year two, roughly 1 percent of revenue. That recovers 40 percent of the $400,000 decline, so the two stores are not the main story. I would close them and spend the rest of this case on where the other $240,000 went." Score four counts: set-up before arithmetic, answer rounded, answer interpreted against the question, and the assumption that matters (the 25 percent transfer) said aloud.
Rep three, the close. Read your notes for 30 seconds, then deliver a 60-second recommendation. Count: recommendation in the first sentence, a number in it, one risk (the transfer rate is a guess; at 10 percent the year-one gain turns negative), one next step.
Twelve minutes, three reps, a page of counts. Repeat with the next free prompt; that is what the firm pages are for.
Practice this today
Open one firm case; Bain's Coffee Shop Co. or any of McKinsey's four will do. Run the three reps above with your phone and write the counts down before you look at the model answer. A dozen prompts is enough to start, and the firm pages supply that; the thirty-first free link is an evening spent not doing a case.
If you want the counting done for you, CoachNed's five-minute first rep takes three typed turns of a case and scores them instantly, no account needed. The math drill scores the spoken set-up problem from rep two against an answer key, and quick math is free forever. The voice case with Ned runs about 18 minutes and ends in a seven-score debrief, and the case library has 64 original cases for when the firms' own run out. Everything is open for seven days, no card; then $120 for a recruiting season or $49 a month.
CoachNed is independent and not affiliated with McKinsey, BCG, Bain, or any other firm named here.
Frequently asked questions
Can you prepare for a case interview for free?
Yes, for everything except the score. The firms publish prompts, model answers, and their own account of what they look for; a phone recorder and a written rubric supply the feedback loop. Budget hours, not money, and spend them speaking rather than reading.
Are McKinsey's practice cases free?
Yes. As of September 2026, McKinsey's interviewing page carries four practice cases with suggested answers and PEI question previews, no sign-up needed.
Are MBA casebooks still worth using?
As prompt and exhibit libraries, yes. As teaching, no: the frameworks date and the model answers are unedited student work, so check every number and treat a disagreement with the key as a rep in itself.
Is there a free case interview simulator?
Deloitte's interactive case tool is free and untracked, and CoachNed's first rep runs without an account. Deloitte checks your answers; CoachNed scores how you got there, which is what the interview grades.
Sources
- Interviewing at McKinsey — the four practice cases, PEI previews, AI-use table, and Solve description. Checked 2026-09-24.
- BCG case interview preparation — BCG's description of the case, the do and don't lists, and OneDay@BCG. Checked 2026-09-24.
- Bain practice case: Coffee Shop Co. — the worked breakeven and the one-to-two-minute structuring pause. Checked 2026-09-24.
- Interviewing at Bain — digital assessment, then case interviews, for consulting roles. Checked 2026-09-24.
- Deloitte case and scenario interview tips — the five-step approach, the "right answer" statement, and the link to the interactive case tool. Checked 2026-09-24.
- Oliver Wyman interview preparation — the six-step case method and practice samples. Checked 2026-09-24.
- Management analysts (BLS Occupational Outlook Handbook) — median pay of $101,860 in May 2025 and about 94,100 projected openings a year. Checked 2026-09-24.