McKinsey, Bain, BCG Case Interview Prep Tools (2026)

Which case interview prep tool belongs to which firm

Every tool belongs to someone, and the owner decides what it covers and how long it stays true. Sorting the list by owner rather than by skill changes its shape.

Four cases plus two cases plus thirteen modules is nineteen items. Thirteen of those nineteen are BCG's modules, and all thirteen live off BCG's own domain. Recomputed by hand on 7 October 2026: 13 divided by 19 is 0.6842, so 68 percent of the official practice material is one firm's simulation library sitting on somebody else's platform.

That number explains why official tool lists read thin. Two of the three publish six worked cases in total. Everything else in the inventory is either a simulation of the job or a sample of a screening interface.

The second consequence matters more. A tool hosted elsewhere carries that host's account, its enrollment flow and its data handling. BCG links to the platform from its own page, so the arrangement is visible, and it is worth a minute of reading before you sign up.

McKinsey publishes a permissions table for prep tools

One of the three publishes rules about preparation rather than only about the room. Its interviewing page carries six lines, three encouraged and three not allowed.

The firm states its reasoning in two sentences on the same page: "When used responsibly, we see AI as a valuable tool that supports preparation." And then: "Misuse, however, compromises fairness." That is the only published position on prep tools among the three, and it draws the line at the moment the exercise starts.

A second McKinsey page, its assessment integrity expectations, sets what you may hold. Pen and paper only for notetaking and calculations, with a note that the firm may ask to review those notes to understand your thought process. Candidates must refrain from "using any applications or websites, generative AI, a calculator, or prepared notes". They are asked to "discard any notes taken during the assessments/interviews".

The firm's four practice cases are the tool its own page recommends: "These cases contain logic, thought processes, and suggested answers." One of them, Electro-Light, publishes a price of $2 to retailers, a unit cost of $1.90 and $40 million in fixed costs. Unit contribution is $0.10, so the break-even is $40,000,000 divided by $0.10, which is 400 million bottles. The page describes a 16 ounce bottle as one eighth of a gallon, so 400 million bottles is 50 million gallons. The same page tells you how to do that: "Remember that calculators are not allowed."

About its assessment, the firm writes "There's no need to prepare". No duration appears anywhere we read. Your invitation email carries it.

BCG hosts its prep tools elsewhere

BCG publishes no case library of its own. What it publishes is a job simulation set, described on its virtual experience page as "BCG's free, virtual job simulations. With 13 unique modules to choose from".

Two statements on that page are usable and two are not. Usable: participants "Receive real-world sample answers from our leaders, top-tier consultant, and designers", and one shortened module covers "how to frame effective questions, think more creatively, and learn techniques for effective brainstorming". That maps onto a brainstorming exercise directly, and it is the closest thing BCG offers to a worked answer.

Not usable: the page says the simulations help you "Stand out on your BCG application" and attaches no figure. It separately publishes a participation count above 700,000 with no period and no method. Neither statement supports a claim, so this page makes none.

The firm's clock sits on a different page. Its US Associate page states that the career assessment is sent 30 to 90 minutes after you submit your application, takes approximately 30 to 35 minutes, and must be completed within 48 hours of receiving the invitation. A select group is then invited to an online case about two weeks after the application deadline, running roughly 35 minutes.

Those three figures combine into a planning number the page does not state. Forty-eight hours is 2,880 minutes. Take away a 35 minute sitting and 2,845 minutes remain, which is 47 hours and 25 minutes of latitude about when you sit it. That figure is derived from two published numbers rather than read off the page, and it holds for the US Associate process only.

Our BCG online assessment guide holds the format detail, with a career assessment diagnostic and a chatbot case rehearsal built around the published shapes.

Bain recommends a tool for one of two tests

Bain sends one of two different assessments and the email tells you which. Its digital assessment page then gives two different sets of advice, which is the fact a tool list sorted by vendor hides.

For Sova the firm writes: "We recommend you look at the candidate preparation area of Sova's website, which contains some sample assessment questions". For Test Gorilla it writes "No preparation is needed". So whether a prep tool is recommended to you depends on an email you have already received, and no published criterion says who gets which test.

One rule covers both. "The use of AI tools are strictly prohibited; this includes recording, screenshots, or use of any software that transcribes or provides feedback during the assessment." A scoring tool is therefore a preparation tool here and nothing else.

The vendor's own hub, read 30 September 2026, publishes a free practice test covering situational judgment questions, video interview questions and three types of ability question. It states that "Your answers to the practice questions do not count towards your score on the assessment." It also says the activities you see are "selected by your potential employer", which is why no page can tell you the composition of yours. And it asks for "a pen, paper and calculator for the ability questions".

On the interview side Bain names two practice cases of its own, Coffee Shop Co. and FashionCo., each linked to a full case study from its case interview page. The same page describes what it offers as "Bain-designed materials, sample cases, practical tips, and trusted external resources". Our Bain assessment guide and a free vendor-format sampler cover the screening half.

McKinsey, Bain, BCG case interview prep tools by stage

The right tool depends on which stage is next, and the published rules differ by stage more than by firm.

Five decisions follow from that table, in order.

1. Read your invitation email before buying anything. It names your stage, and at two of the three firms it is the only document that does.
2. Do the six published cases before any other case. Four at McKinsey and two at Bain, each with the answer attached, which is what makes them self-checkable.
3. Use a simulation set for the screening interface and nothing else. BCG's thirteen modules teach task familiarity, and the firm attaches no claim beyond that.
4. Put the calculator down four weeks out. That interval is ours and no firm publishes one. It exists so the paper habit is in place before mocks start.
5. Write nothing you plan to carry in. Prepared notes are listed among the things McKinsey asks candidates to refrain from, so a cheat sheet is a study aid and never a prop.

What our simulators add, and what they skip

We sell graded practice, so the honest description comes with its limits. Our six assessment simulators rehearse the formats these firms screen with, including a research-study format, a constraint-satisfaction format and a ranking format. None of the six is live yet, and that page says so.

The module names on those pages are the names candidates use. No page published by BCG or McKinsey carries them, which we checked across a 566 URL sitemap. The format is the thing being rehearsed and the label is a signpost.

Our six graded drills do something the firms' material does not, which is return a score on a named dimension. The weights come from our own grading code and they are ours alone.

What none of the three publishes about its tools

Five absences, each checked page by page on 7 October 2026.

1. A mark scheme. None of the three publishes one, for any exercise. Every weight on this page is ours and labeled as ours wherever it appears.
2. A duration for McKinsey's assessment. The firm defers it to the invitation email, which is a decision rather than an omission.
3. A per-module running time for BCG's thirteen. Absent from the page we read.
4. Any measured effect of a free module on an application. BCG writes that the simulations help you stand out and gives no figure, so neither will we.
5. Whether a digital badge is ever looked at by a recruiter. Nothing published says it is.

One absence has a published cause worth naming. McKinsey asks candidates to refrain from "sharing information about the content of their assessment/interview with others (such as specific questions, problem solving scenarios)". Detailed public accounts of its assessment are therefore scarce by design, and any product that promises an exact replica is either describing a published format or breaking that rule.

One market sells those replicas in the open, with every price on a public page. Our review of nine paid assessment simulators and the terms attached to them adds the nine prices up against the platform plan that covers the same tests, records the access term on each, and quotes the refund clauses that sit behind the advertised guarantee.

One question this page leaves open on purpose. School casebooks sit outside the inventory above because none of the three firms publishes one, and because a copy hosted by somebody else is a rights question before it is a quality question. Our case book vault states what each collection is and where it legitimately comes from, which is the honest version of that answer.

Two gaps no tool on this page closes. Nothing here interrupts you mid-structure, and nothing asks you to defend a number you have already given. Those need a person, which is what case practice partners and mock case interviews are for.

For the tool list organized by the dimension each one trains rather than by the firm that owns it, case interview tools carries that axis and the full calculator rule. For how to split preparation hours across the three firms once you have the tools, MBB case interview prep counts what each firm publishes about its process. Firm by firm, there is McKinsey, BCG and Bain.