Case Interview HQ

Think like a consultant before your first case.

Free, current guides to McKinsey, BCG and Bain recruiting, and three practice books by Stephan Spijkers. Learn to structure any case, pass the online screen and walk into the final round prepared.

Read the case interview guideSee the three books
60 guides, updated October 2026Books used by candidates since 2012No sign-up
A profitability issue tree Profits down 18 percent splits into revenue and costs. Revenue splits into volume and price; costs split into fixed and variable. Variable costs are highlighted as the working hypothesis. Profits down 18%in two years Revenueflat, +1% Costsup 14% Volume Price Fixed Variableinputs +31% hypothesis: input costs drive the drop
The profitability tree, the first structure most candidates draw.From Cracking the Case

Four gates stand between your application and an offer.

Each gate tests something different. Prepare for the one in front of you, then the next.

  1. Resume screen

    A recruiter scans your resume and cover letter in about 30 seconds.

    100 of 100 applicantsWrite a consulting resume

  2. Online assessment

    McKinsey Solve, BCG’s online case or Bain’s aptitude test.

    33 of 100 applicantsPrepare for the online test

  3. First round

    Two or three live cases plus a fit interview with consultants.

    8 of 100 applicantsMaster the case interview

  4. Final round

    Partner cases where judgment and synthesis decide.

    3 of 100 applicantsCommunicate top-down

Illustrative estimate. McKinsey has reported offer rates near 1% of applicants; stage rates combine that figure with candidate reports and prep-provider estimates.

Three books that cover every gate.

One playbook for the live interview and two full practice tests for the data-heavy screens. Written from first-hand experience on both sides of the table.

Case Interview HQ Crackingthe Case Stephan Spijkers

Cracking the Case

The complete case interview playbook

Everything from the cover letter to the partner round in one book, written by someone who has sat on both sides of the table.

  • A cover letter and resume method built around the 30-second scan
  • One answering method for every personal-fit question
  • Four principles for guesstimates and market sizing, with the pitfalls to avoid
  • Three business-case frameworks and when to drop them
  • Three cases solved by a real candidate across 30+ annotated pages
  • A brainteaser approach with seven practice puzzles
€27Buy nowWhat’s inside
Case Interview HQ The Keyto the PST Stephan Spijkers

The Key to the PST

A full written-case practice test

A complete 26-question timed test with a step-by-step answer guide. It trains the skills every online screen rewards: reading dense exhibits, calculator-free math and finding the client’s real question.

  • 26 multiple-choice questions across several business cases
  • Designed to be taken in 60 minutes without a calculator
  • A full answer guide that shows the fastest route to every answer
€17Buy nowWhat’s inside
Case Interview HQ The SecondKey to the PST Stephan Spijkers

The Second Key to the PST

A second full test with fresh cases

Once you have the method, you need more material that behaves like the real thing. Another 26 questions, new clients and the same detailed answer guide.

  • 26 new questions across fresh business cases
  • Same timing and difficulty as the first test, so scores are comparable
  • Detailed worked answers for every question
€17Buy nowWhat’s inside

The Prep Pack: all three books

The full playbook plus both practice tests, for 40% less than buying them one by one.

€61€37Get the Prep Pack

The PST is retired. Its skills are screened harder than ever.

Update for 2026: McKinsey replaced the Problem Solving Test with Solve, a gamified online assessment.

The test changed format. The work underneath stayed the same: pull the right numbers from a crowded exhibit, calculate without a calculator and answer the question the client actually asked. The two practice tests drill exactly that.

How McKinsey Solve works in 2026

Skill the books trainMcKinsey SolveBCG online caseBain aptitude testLive case
Reading dense exhibits fastTestedTestedTestedTested
Calculator-free mathTestedTestedTestedTested
Finding the client’s real questionPartlyTestedPartlyTested
Hypothesis-driven structureTestedTestedPartlyTested
Synthesis under time pressurePartlyTestedPartlyTested

Based on published firm guidance and 2026 candidate reports. Formats vary by office.

Every guide on the site.

Organized the way the recruiting process runs. Each guide opens with a short answer, then the detail.

Case interviews

How live cases work, how to structure them and how each firm runs them.

Online assessments

McKinsey Solve, BCG’s online case and Bain’s aptitude tests, plus the written-case skills behind them.

Frameworks

MECE, the Pyramid Principle and the structuring habits interviewers score.

Firm profiles

The history and culture of McKinsey, BCG and Bain, and what it means for your interview.

Applications

Resumes, cover letters, screening and what to wear on the day.

Consulting careers

Salaries, hours and whether you need an MBA.

Written by someone who has sat on both sides of the table.

Stephan Spijkers founded Case Interview HQ in 2011 after working through the strategy consulting selection process himself: written test, case rounds and partner interviews. He has interviewed candidates from the other side of the table, coached students one-on-one and in group sessions, and wrote Cracking the Case and the two Key to the PST practice books. Today he runs PIMvendors.com, a product information management consultancy.

More about Stephan

“I used your book to prepare and it was really helpful. I just heard that I passed the test, and I finished with about 10 minutes to spare to review the questions I was unsure of.”

Reader, after passing McKinsey’s written test

Questions candidates ask first.

Is the McKinsey PST still used in 2026?

No. McKinsey replaced the paper Problem Solving Test with Solve, a gamified online assessment. The skills the PST measured (reading dense data, calculator-free math and finding the client’s real question) are still screened in Solve, BCG’s online case and Bain’s aptitude tests.

Which book should I start with?

Start with Cracking the Case if you have case interviews coming up. Add The Key to the PST when you face an online screen with data interpretation, and take The Second Key as a second timed run. The Prep Pack bundles all three for €37.

Are the guides free?

Yes. All 60 guides on the site are free to read, with no sign-up. The books go deeper with full practice tests, worked cases and answer guides.

How long should I prepare for a consulting case interview?

Most successful candidates practice for four to eight weeks and complete 25-40 live cases with a partner, alongside daily mental math and structured reading.

What format are the books?

All three are PDF e-books delivered instantly after purchase, in an English and a Dutch edition. You can read them on any device or print them to take the practice tests on paper.