McKinsey vs BCG vs Bain: how the interviews differ

Interviewer-led versus candidate-led cases, the PEI, online assessments and written cases: what McKinsey, BCG and Bain each look for and how to adjust. 6 min readUpdated 11 November 2026By the Prepper team

McKinsey, BCG and Bain test the same abilities with different formats. Knowing the differences lets you practise the right way for each firm.

Before the interviews

McKinsey: the Solve game-based assessment.
BCG: the Casey chatbot case, about 35 minutes with a short video answer.
Bain: an online test in some offices.

Details are in consulting online assessments compared.

The case

McKinsey: interviewer-led. The interviewer asks a sequence of set questions: structure, a calculation, a chart, a brainstorm, a recommendation. Each answer is judged on its own, so every one needs a clear structure.
BCG: candidate-led. You decide where to go next and ask for data. Expect a creative brainstorm and a numerical exhibit, and be ready to defend your hypothesis.
Bain: candidate-led, with frequent market sizing and a practical, results-first tone. Many offices add a written case in the final round, where you read a pack of slides and present a recommendation.

The fit part

McKinsey's Personal Experience Interview goes deep on one story about leadership, personal impact or drive, with many follow-ups. See the PEI guide.
BCG and Bain ask a broader set of shorter fit questions: why consulting, why this firm, a team conflict, a failure.

How to adjust your practice

For McKinsey: practise answering single questions in a structured way within two minutes, and prepare three PEI stories in great detail.
For BCG: practise leading. After every answer, say what you want to look at next and why.
For Bain: drill market sizing and practise one written case under time pressure.

What does not change

Structured thinking, accurate mental maths, a clear recommendation and being pleasant to work with. The case interview guide covers these foundations.

Frequently asked questions

Is McKinsey's interview harder than BCG's or Bain's?
The standard is similar. McKinsey's format is more controlled and its fit interview goes deeper on one story; BCG and Bain expect you to drive the case.
Can I prepare for all three at once?
Yes. Build the shared skills first, then spend the last week before each interview practising that firm's format.

Is McKinsey's interview harder than BCG's or Bain's?

The standard is similar. McKinsey's format is more controlled and its fit interview goes deeper on one story; BCG and Bain expect you to drive the case.

Can I prepare for all three at once?

Yes. Build the shared skills first, then spend the last week before each interview practising that firm's format.