Written Case Interview: Format, Firms, and How to Crack It (2026)

Last Updated on June 4, 2026

By Florian Smeritschnig, former McKinsey Senior Consultant · Updated June 2026

A written case interview hands you a thick pack of data — 20 to 50 slides — and roughly one to two hours to analyze it, answer several questions, and turn it into a short, defensible slide deck, which you then present and defend. It’s the live case with the clock made visible and your thinking written down. Most candidates drown in the data pack. The ones who pass decide what matters fast and build the story around it.

I spent years at McKinsey reviewing exactly this kind of output for CEO meetings, and I’ve coached hundreds of candidates through Bain, BCG, and Strategy& written cases. The format rewards one instinct above all: ruthless prioritization under time pressure. This guide covers what a written case interview is, the five stages you move through, the six-step method that works across firms, and exactly how Bain, BCG, Strategy&, and Deloitte each run their own version.

Key Takeaways

• A written case interview means analyzing a data pack (20-50 slides) in ~1-2 hours, building 3-5 recommendation slides, then presenting and defending them.
• It’s usually a final-round step and varies by office. Not every firm or every office uses it.
• Firms differ mainly in the fact pack: BCG gives ~2 hours and allows calculators; Bain gives ~55 minutes and bans them (pen-and-paper only).
• The same six-step method works everywhere: plan → cut the noise → read the exhibits → do quick math → build the storyline → defend the recommendation.
• The output is judged like a partner deck: action titles that state the “so what,” clean visuals, top-down logic.

What is a written case interview?

A written case interview — sometimes called a written case study — is a consulting interview format where you receive a pack of business data (text, slides, charts, tables, and client questions) and work alone for a set time to produce a short slide deck with your recommendation, which you then present to interviewers and defend in a Q&A. It tests the same problem-solving as a live case, plus synthesis, exhibit reading, and the ability to build a clear output under time pressure.

In short: same thinking as a live case, but you do the structuring on paper and hand in a deck.

When the written case happens

The written case is almost always a final-round exercise, after the resume screen and any online assessment (like BCG’s online case). It isn’t universal; whether you face one depends heavily on the firm and the specific office. Bain and BCG run it in some regions and not others; Strategy& and Deloitte use their own variants. If you’ve been invited to a final round in Europe or Asia especially, it’s worth asking your recruiter whether a written case is part of the day.

What a written case interview tests

The written case is designed to surface the skills a live case can hide. Across firms, interviewers score the same cluster:

• Synthesis under overload: pulling the few decision-relevant facts out of a 40-slide pack.
• Exhibit reading: turning charts and data tables into insight quickly.
• Quick, clean math: pen-and-paper estimates and calculations, not heavy computation.
• Storylining: building a top-down argument a partner could act on.
• Communication and defense: presenting clearly, then holding up under challenge.
• Composure: staying organized when there’s far too much information and far too little time.

How a written case works: the five stages

Almost every firm’s written case moves through the same five stages. The clock changes; the shape doesn’t.

1. Receive the case. You get the prompt, the client question, and the data pack, plus blank or partly built slide templates.
2. Form hypotheses and analyze. You decide what to test, then mine the pack for the evidence that proves or breaks it — not every number, just the ones that move the answer.
3. Build the slides. You draft 3-5 output slides: a recommendation slide, supporting slides, and a next-steps slide.
4. Present. You walk interviewers (acting as the client or project leader) through your deck, top-down, usually in 15-20 minutes.
5. Q&A. They challenge your logic, your math, and your assumptions for another 15-20 minutes.

How the written case differs by firm

The thinking is constant; the fact pack is not. Here’s how the major firms’ written cases compare.

Match your prep to the one you’ll actually sit.

What about McKinsey? McKinsey doesn’t run a standalone written case. Its equivalent screens are the McKinsey Solve assessment and live, interviewer-led McKinsey cases; so if McKinsey is your target, prepare those instead.

The BCG written case

BCG runs the longest, most data-heavy version. You get roughly two hours to prepare (within a ~2h40m total block) from a pack of around 40 slides, and you produce 3-5 output slides, then present for about 15 minutes and defend for another 15. Calculators are allowed, but there’s a catch most candidates underestimate: you generally can’t write on the materials, which makes tracking your thinking across 40 slides genuinely hard.

The defining challenge is information overload, far more data, charts, and press clippings than you can read end to end. The job isn’t to analyze everything; it’s to form a hypothesis and calculate only what tests it. A typical pack centers on a market-entry or growth question, with the kind of prompts you’ll be asked to take a position on:

• “I think the client should enter the Chinese market first. Do you agree? What would make China attractive to them?”
• “Which product category has the best chance of being successful and profitable in China?”
• “What are the strengths of the client that let its products compete in the Chinese market?”

A workable time split for the two-hour prep: 5 min scanning the pack, 5 min planning your approach, 20 min drafting empty output slides, 70 min running the analysis, 20 min populating the slides. The math itself is usually straightforward (e.g., “manufacturing cost increased 25% over three years”). Speed and selection matter more than computational firepower. For the format’s broader context, see our BCG case interview guide.

The Bain written case

Bain’s version is shorter and tighter: about 55 minutes to prepare (within a ~1h35m block) from 20-30 slides, some of them part-built templates you complete. Calculators are not allowed — it’s pen-and-paper math and estimation throughout. You then present your conclusions for 15-20 minutes and take Q&A for another 15-20. It shows up mostly in European and Asian offices in the second round.

Bain’s own guidance to candidates captures the mindset: trust your gut — there is no single right answer. They’re testing whether you can commit to a defensible point of view under time pressure, which is the same answer-first instinct the live Bain case rewards (more on that in our Bain case interview guide).

A workable split for the 55-minute prep: 2.5 min scan, 2.5 min plan, 10 min draft output slides, 30 min analysis, 10 min populate. For a 30-minute variant, roughly halve each step.

Strategy& and Deloitte written cases

Strategy& (PwC) often runs a take-home variant: you receive a full document set up to 48 hours in advance, build a PowerPoint deck on your own machine, and present it for 20-30 minutes followed by 15-30 minutes of discussion. More time, higher polish expected.

Deloitte (and the legacy Monitor format) mirrors Bain: a slide pack, 50-60 minutes of prep, and a ~40-minute present-and-defend session.

How to crack a written case: a six-step method

This is the sequence I drill with candidates, and it holds whether you have 55 minutes or two hours.

1. Plan before you start. Read the question first, set a time budget for each stage, and decide your output slides before you analyze. You’re building to a deck, not exploring.
2. Separate signal from noise. Skim the whole pack once to map what’s there, then ignore everything that doesn’t bear on the question. Most of the data is a distractor.
3. Read the exhibits fast. Train yourself to state the “so what” of any chart in about 30 seconds. Our chart interpretation drills are built for exactly this.
4. Do quick pen-and-paper math. Set up the calculation, estimate cleanly, and sanity-check the magnitude. Speed and accuracy here come from case math practice, not from a calculator.
5. Build the storyline. One recommendation slide, a few supporting slides, one next-steps slide. Each with an action title that states the conclusion, not the topic (“Weak digital spend drives the share loss,” not “Marketing analysis”).
6. Communicate and defend. Present top-down: recommendation first, then evidence, then risks and next steps. In Q&A, defend your logic but revise gracefully when the data pushes back. Sound case structuring and case communication underneath makes the defense easy.

Common written-case mistakes

The same failure modes sink strong candidates again and again:

1. Reading everything. Trying to digest all 40 slides leaves no time to build the deck. Decide what matters, then go deep only there.
2. Starting analysis before planning the output. If you don’t know your slides up front, you’ll produce findings that don’t add up to a story.
3. Topic titles instead of action titles. “Market overview” tells the interviewer nothing. Every title should carry the insight.
4. No clear recommendation. Strong analysis with a hedged ending fails the exercise. Take a position and defend it.

How to prepare for a written case interview

Most written-case prep fails the same way most case prep fails: candidates chase volume instead of building the underlying skill. The written case rewards synthesis and output craft, and those are trainable directly.

A better sequence:

• Practice on real packs. Public business cases from Harvard Business Publishing, Ivey, INSEAD, and MIT Sloan are close to written-case material.
  • HBS case studies
  • Ivey case studies
  • MIT case studies (includes free materials)
  • INSEAD case studies
• Drill actual written cases provided by different firms for preparation.
  • BCG Chateau Boomerang
  • Bain Coffee Shop Co
  • Bain FashionCo
  • Deloitte Footloose
  • Our collection of consulting case examples is another starting point.
• Drill the sub-skills. Exhibit interpretation and pen-and-paper math under a timer, since those are where time is won or lost.
• Build to a deck every time. Don’t just “solve” the case; produce 3-5 slides with action titles, so the output becomes a reflex.
• Get honest feedback from someone who has built and reviewed real consulting decks with McKinsey. You can’t self-diagnose a weak storyline. That’s where 1-on-1 coaching earns its keep, and it’s the gap StrategyCase is built to close.

BCG’s and Bain’s own careers sites (BCG, Bain) are worth checking for current, office-specific interview details, since the written case varies so much by location.

Frequently asked questions

Related guides

• Complete case interview guide: our core guide on case interviews where written-case skill sits under
• Case structuring guide: learn how to build the framework speed a written case demands
• Exhibit interpretation guide: learn the 3-step method to analyze every chart
• Case math guide: set up math formulas and execute calculations quickly
• Market sizing cases: the estimation sub-skill written cases lean on
• Best case interview books:what to read, and what to skip for your overall consulting interview prep

Final word

The written case interview looks intimidating because of the data pack, but it rewards a simple discipline: plan your output, cut the noise, and build a clean story you can defend. Match your prep to the firm and office you’ll actually sit — BCG’s two-hour data dump and Bain’s 55-minute pen-and-paper sprint are different animals — and practice building to a deck until it’s automatic.

The process is tough, but it’s conquerable with the right preparation. Start with StrategyCase’s complete case interview preparation and build the synthesis instinct that written cases reward.

About the author: Florian Smeritschnig is a former McKinsey Senior Consultant and the founder of StrategyCase. He has run 2,200+ mock case interviews and coached hundreds of candidates into McKinsey, BCG, Bain, and other top firms.