McKinsey interview: case interview, personal experience and online assessment
· 8 min read
Consulting interviews are often reduced to the case interview alone. That is an expensive preparation mistake: at the major strategy firms, the interview devoted to your personal experience carries just as much weight, and candidates rehearse it far less.
What exactly is the case interview?
You are given a business problem — a collapsing margin, a market to size, an investment decision — and you must structure it out loud with the interviewer. The format is conversational: you ask questions, you receive data, you conclude. It is not a test of industry knowledge. It is a test of structuring: cutting a vague problem into clean parts without missing one.
Should you memorise analytical frameworks?
No, and reciting them is a negative signal. Classic frameworks exist so you forget nothing, not to be announced. A candidate who declares "I will apply a four-part framework" before understanding the problem disqualifies themselves; a candidate who proposes a breakdown tailored to this specific case scores immediately. The useful rule: your structure must be exhaustive and non-overlapping, and it must come from the problem in front of you.
Is mental arithmetic really disqualifying?
- Not in itself, but an order-of-magnitude error almost always is: it suggests you do not check your own results.
- Practise percentages, ratios and division on large numbers, without a calculator and while speaking.
- Announce your calculation before doing it — that lets the interviewer correct you early, which helps you.
- Round deliberately and say so. Working in orders of magnitude is seen as a skill, not a shortcut.
What is the personal experience interview and why does it eliminate?
It is a deep interview on two or three lived situations, usually around leadership, personal impact and resolving a conflict. The difficulty is not finding the story: it is the depth of the follow-ups. You will be asked what you felt, what the other person replied, why you did not act differently. A story prepared at surface level collapses on the third follow-up. So prepare few stories, in great detail.
How does the online assessment before the interviews work?
Most large firms run a digital assessment upstream, and its format changes regularly — problem-solving games, data reasoning exercises. Check the current format with the firm rather than a forum, because descriptions circulating online are often a season or two out of date. The substance does not change: reasoning quickly on incomplete data.
How do you prepare effectively, and with whom?
In pairs, out loud, under conditions. A case worked alone on paper creates an illusion of mastery: the real difficulty is holding your structure while speaking, under pressure. Expect several dozen practice cases before feeling comfortable. Our articles on the Deloitte interview and on the practical case exercise offer points of comparison.
They do not hire the person who finds the right answer. They hire the person whose reasoning they understand well enough to put in front of a client.
Finally, prepare your own questions: in consulting they genuinely count. See questions to ask the recruiter.