sennaMcKinsey interview guide
Prepare for the case interview, personal experience interview and Solve assessment with a detailed, practical guide—complete with original examples, visual explanations and a 14-day study plan.
Try a worked case →See study plan
McKinsey interview process: what to expect
McKinsey evaluates how you solve ambiguous business problems and how you have made a difference in real situations. The process varies by role, office and candidate; the official recruiter instructions take precedence.
CV and role-specific screening.
Solve or a role-specific test when required.
Detailed examples of your individual impact.
Structure, quantitative reasoning and synthesis.
Illustrative sequence only. Actual ordering and number of stages vary. Source: McKinsey careers interviewing guidance.
How to solve a McKinsey case interview
A case is a conversation about a client problem, not a written exam. Start by clarifying the decision, structure your analysis into non-overlapping drivers, prioritise the most important branch and update your hypothesis as evidence emerges.
- Clarify: What decision must the client make, by when, and against which success metric?
- Structure: Break the problem into testable drivers rather than reciting a generic framework.
- Prioritise: Identify the highest-value uncertainty.
- Analyse: Work through numbers and exhibits aloud; sanity-check the result.
- Synthesise: Lead with your answer, evidence, risks and next steps.
Photo: Pexels.
Visual: the case-solving loop
Client objective and constraints
Likely drivers and key questions
Quantify, interpret, challenge
Answer, evidence, risk, action
Common case types and a useful starting question
| Case type | Starting question | Analytical lenses |
|---|---|---|
| Profitability | What explains the change in profit? | Revenue, volume, price, fixed and variable costs |
| Market entry | Should the client enter this market? | Market size, economics, capabilities, competitive response |
| Growth | Where is sustainable growth most attractive? | Customers, channels, products, unit economics |
| Operations | Where is the performance bottleneck? | Capacity, throughput, defects, utilisation |
| Investment | Will the investment create value? | Returns, synergies, risks, alternatives |
McKinsey-style case example: a retailer’s declining profit
Prompt: A regional retailer generated £120 million of sales last year but operating profit fell from £18 million to £9 million. The CEO wants to know why and what to do next. This is an original teaching example, not an actual McKinsey interview question.
Candidate opening
“I’d like to separate the change in profit into revenue and cost effects, then investigate whether the issue is concentrated in particular stores, product categories or customer segments. Before proceeding, has revenue changed or is the issue primarily margin?”
Exhibit 1: revenue and cost bridge
Assume revenue is unchanged at £120m. Operating costs rose from £102m to £111m. The profit decline is therefore entirely attributable to a £9m cost increase.
Illustrative cost breakdown (increase in £m)
Invented figures for learning purposes; not market research or McKinsey data.
What a strong candidate would do next
- Test labour productivity: hours per transaction, overtime, scheduling and wage inflation.
- Separate logistics price inflation from delivery inefficiency and order mix.
- Calculate feasible savings, implementation costs and customer-service trade-offs.
- Recommend targeted pilots instead of a blanket cost cut.
Case interview maths and charts
Make the calculation easy for the interviewer to follow: state the formula, estimate cleanly, calculate and interpret the answer in business terms.
Customers × usage frequency × average spend.
Price − variable cost per unit.
Fixed costs ÷ contribution margin.
Practice question: break-even
A product sells for £50, has £30 variable cost per unit and requires £2m of fixed investment. How many units must the company sell to break even?
Reveal worked answer
Contribution margin = £50 − £30 = £20. Break-even units = £2,000,000 ÷ £20 = 100,000 units. A strong answer would also ask whether there is sufficient demand and whether fixed costs are truly fixed.
Illustrative case practice time allocation
Suggested self-study mix, not an official McKinsey weighting or assessment rubric.
McKinsey Personal Experience Interview (PEI) preparation
McKinsey asks for specific experiences where you made a difference. Prepare more than a headline: the interviewer may probe your decisions, relationships, trade-offs and what you personally did.
Its official guidance recommends preparing two detailed examples in each of four impact areas. Check the latest themes and wording on the official interview page.
Photo: Pexels.
Build a story that withstands follow-up questions
What was at stake?
What were you responsible for?
What did you decide and do?
What changed and what did you learn?
PEI practice prompts
Tell me about a time you persuaded someone who strongly disagreed with you.
Describe a difficult goal you achieved under significant constraints.
Tell me about a time you helped people with different perspectives work together.
Tell me about a decision you made with incomplete information.
McKinsey Solve assessment: what candidates should know
McKinsey describes Solve as a gamified assessment of natural problem-solving abilities for many consulting applicants. The firm says preparation is not required and assesses performance alongside the rest of an application. Not every applicant takes it.
Use your invitation and official technical guidance.
No unauthorised tools, assistance, notes or screenshots.
Read carefully, track constraints and check choices.
14-day McKinsey interview preparation plan
This is a suggested schedule, not an official McKinsey programme. Adjust the workload to your experience and interview date.
| Days | Focus | Deliverable |
|---|---|---|
| 1–2 | Read official guidance; diagnose strengths and gaps | Baseline case and PEI inventory |
| 3–4 | Profitability and market sizing | Two reviewed practice cases |
| 5–6 | Data exhibits and mental maths | Calculation error log |
| 7–8 | PEI stories with probing follow-ups | Eight evidence-rich stories |
| 9–10 | Market entry, growth and operations | Three practice cases with feedback |
| 11–12 | Mixed mock interviews | Prioritised improvement list |
| 13 | Final weak-area practice | Concise synthesis examples |
| 14 | Light review and logistics | Ready-to-use interview setup |
Final-day checklist
- Know the role and office you applied to
- Confirm time zone and interview format
- Test camera, microphone and connection
- Review two strong examples per PEI area
- Practise a crisp recommendation
- Prepare thoughtful questions
- Have pen, paper and water if permitted
- Follow assessment integrity instructions
Common McKinsey interview mistakes—and better alternatives
| Less effective | Stronger alternative |
|---|---|
| Reciting a memorised framework | Build a structure around the client’s actual decision |
| Calculating silently | Explain the formula and interpret the business implication |
| Overexplaining the background of a PEI story | Focus on your decisions, conflicts and individual contribution |
| Giving an answer without a recommendation | Lead with a decision, then evidence, risk and next step |
| Assuming one case format everywhere | Listen to the interviewer and adapt |
| Using unauthorised help during an assessment | Follow McKinsey’s integrity rules strictly |
Official McKinsey resources and related career guides
Official descriptions of case interviews, PEI, sample cases and role-dependent assessments.
Official interview guide →Official overview, candidate expectations and assessment integrity rules.
Solve guidance →Explore another analytical interview track with Senna’s existing guide.
Read Senna guide →More Senna career intelligence
Essential AI skills for finance professionals · The rise of data jobs in finance
McKinsey interview FAQs
What is the McKinsey interview process?
For many client-facing consulting roles, McKinsey describes personal experience and problem-solving (case) interviews. Some candidates may also complete the Solve assessment and, depending on role, an expertise or technical assessment. Your recruiter will confirm the actual steps.
Is the McKinsey case interview interviewer-led?
Many McKinsey cases are interviewer-guided, but formats vary. Practice responding to specific prompts, making your thinking visible, and adjusting your structure when new information arrives.
What is the McKinsey Personal Experience Interview (PEI)?
The PEI explores real situations where you made an impact, overcame challenges, influenced others or led inclusively. McKinsey recommends preparing detailed examples that show your own decisions and actions.
How do I prepare for McKinsey Solve?
McKinsey says Solve is designed to assess natural problem-solving and that preparation is not required. Follow the official instructions and integrity rules. Do not use AI, external assistance, notes or screenshots during the assessment unless McKinsey has approved an accommodation.
How many cases should I practice?
There is no official universal number. Focus on variety and feedback: practice structuring, maths, exhibit interpretation and synthesis until you can explain your reasoning consistently.
Are McKinsey interview questions the same for all offices?
No fixed set of questions or stages applies to every role and location. Treat examples in this guide as practice material, not leaked or guaranteed interview questions.
What should I ask at the end of a McKinsey interview?
Ask about the interviewer’s work, team development, feedback culture, client problem solving, and what success looks like in the role. Make the questions specific to your interests.
Can I use AI during my McKinsey interview or Solve assessment?
Follow McKinsey’s assessment-integrity rules. Its Solve guidance expressly prohibits AI tools and external assistance during the assessment except where an accommodation has been approved in writing.
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