Case Interview Tools: What Each One Actually Trains

The rule that comes before the list

McKinsey's assessment integrity expectations set out what candidates may use. Pen and paper only for notetaking and calculations, and it adds that the firm may ask to review your notes during the interview to understand your thought process. Among the things candidates must refrain from: using any applications or websites, generative AI, a calculator, or prepared notes.

Bain draws the same line in a different place. Its digital assessment page allows pen, paper and a calculator, and says calculators are allowed for that assessment only and not during any subsequent interviews. And McKinsey's own Electro-Light case reminds candidates on the page that calculators are not allowed, suggesting they write out the calculations on paper instead.

So a tool can build a skill and still mislead you if you use it up to the round. The switch to paper has to happen while you still have weeks. Handwriting a chain is slower than typing one, and discovering that in a final round is expensive.

Official case interview tools, and what they are for

Three firms and one assessment publisher publish something usable at no cost, and each covers a different part of the process.

BCG's virtual experience page describes its 13 free modules, hosted on a third-party learning platform, and says participants receive real-world sample answers from its leaders, consultants and designers, plus digital badges. One module is described as covering how to frame effective questions, think more creatively and use brainstorming techniques, which maps onto the brainstorming dimension directly.

The page also says the modules help you stand out on a BCG application. That is the firm's phrasing and it carries no number, so treat it as encouragement rather than a measured effect. The page separately publishes a participation figure of more than 700,000, with no period or method attached, which is why we have not built anything on it. BCG is the only firm we found that bundles its own free material this way, and the rest of a toolkit assembled from official parts comes from eleven separately published pieces.

Sova's candidate preparation hub is the right tool for a different problem. Its free practice test covers situational judgment questions, video interview questions and three types of ability question, and it states that practice answers do not count toward your score. It also says the activities in a real assessment are selected by the employer, so it teaches the interface rather than the content.

Our own case interview tools, and what they do not do

We sell graded drills, so here is the honest description. Each one scores one dimension using weights read from our own code, published on our method page.

What they do not do: teach business content. None of the six dimensions above is a knowledge test, and McKinsey's own description of Solve says there is no need to prepare, which is the firm telling you that some of its stages are not content exams either.

They also do not reproduce interview conditions, since they run on a screen. Use them to build the dimension and then move to paper, which is the transition the table in the first section makes mandatory.

One caution about the third-party hosting. BCG's modules live on a platform the firm does not own, so the enrolment flow, the account and the data handling belong to that platform rather than to BCG. That is worth knowing before you sign up, and it is visible on the links from BCG's own page.

Calculators and spreadsheets, used correctly

There is a legitimate window for an on-screen calculator and it closes before your round.

1. Use one to check, never to compute. Do the chain on paper, say the answer aloud, then verify. The checking is what builds confidence in the paper method.
2. Use a spreadsheet to build exhibits rather than to read them. Constructing a two-variable table teaches you what an exhibit is hiding, which is the Next test weight on our chart rubric.
3. Stop using both four weeks out. That is our number and not a firm's, chosen so the paper habit is established before mocks begin.
4. Never use one during an assessment. McKinsey's list includes applications and websites alongside calculators, and Bain says the use of AI tools is strictly prohibited, including any software that transcribes or gives feedback during the assessment.

Our own break-even calculator and market size calculator sit inside rule one. They are checking tools, and a candidate using them to avoid arithmetic is using them against their purpose.

What to use, by stage

The correct tool depends on which stage is next, and the stages differ enough that a single answer is wrong.

The second row deserves a sentence, because it is the one that costs candidates money. McKinsey writes that there is no need to prepare for Solve and to approach it with curiosity and creativity. Our own simulators exist for the interface and we say on those pages that they teach no business content, because the assessment tests none.

What no case interview tool can supply

A mark scheme from a firm. None publishes one. The weights above are ours and they are labeled as ours everywhere they appear.

A guarantee that a free module affects an application. BCG says its simulations help you stand out and attaches no figure, so neither will we.

And the two dimensions that need a person. A tool cannot interrupt you mid-structure. It cannot ask you to defend a number you have already given. Those are the two gaps our case practice partner page is about, and mock case interviews covers the full-condition version.

One more limit is worth stating. No tool tells you which stage you are facing. That comes from the email the firm sends after you apply, and holding it in one place is what our application tracker does. Choosing a tool before you know the stage is how candidates spend a week on the wrong thing.

For the inventory of everything official and free, the free prep resources page has the list with its limits stated, and case interview videos covers the filmed material the firms publish themselves.

And if the question is which kind of practice to choose rather than which tool, the best platform to practice case interviews for MBB compares the five forms on what each one structurally can and cannot do. And on the narrower question of whether a scoring tool beats a session with a peer, AI case interview tools compared to peer practice sets the two against what each one is able to detect.

This page sorts tools by the dimension each one moves, which is why an official case and a calculator can sit in the same row. The other axis is ownership: McKinsey, Bain and BCG prep tools takes the three firms one at a time, with the rules each one publishes about preparation and the inventory each one hosts.