Best way to prepare for a case interview in the next 7 days

Question

Hi! I have two upcoming case interviews, one next week and another with McKinsey next month. I’ve never done a case before but just finished Case Interview Secrets and started the Crafting Cases course.

One interview will involve solving 2 cases in Excel, which I’ve never done. I’m not sure how to approach this type or how it differs from the usual pen-and-paper style. With limited prep time, what should I focus on, and how can I balance standard case prep with Excel-specific practice? Thank you!

Answer 1

Hi there,

First of all, congrats on your interview invitations - that is already awesome! I would tackle your preparation in 2 phases.

Phase 1: Next 7 days
In 7 days, you’ll get the most out of your time if you split prep into two focused streams:

1. Core case skills (60–70%)
Even for Excel-based cases, the fundamentals are the same: top-down communication, hypothesis-driven work, structuring, identifying the key drivers, interpreting data, and synthesising. Practice at least one full case per day live with an experienced candidate, who can give you actionable feedback. Ideally, do a session with a coach who can spot your weak areas and give you tips asap, and maybe another session towards the end of the week for final refinement.

2. Excel-specific adaptation (30–40%)
You can think of it in three layers:

Data interpretation tools: pivot tables, conditional formatting, and basic functions
Navigation & speed: master navigating Excel sheets and ideally some keyboard shortcuts to move, filter, and format without losing time
Targeted financial practice: if your role might involve it, get familiar with building a business case, simple DCF or basic P&L. This is not common for consulting cases, but it can make you stand out if it comes up. If possible, clarify the scope of the Excel cases with HR before the interview.

Phase 2: Until your McKinsey interview

After the first interviews are over, you'll have some time to dedicate yourself to targeted McKinsey-prep. I would train with someone who has previously passed the McKinsey interviews / is specialized on McKinsey coaching to do the following:

1. Targeted case preparation: McKinsey uses an interviewer-led approach, with often unconventional cases. Prepare specifically for that with similar cases and interviewing style.

2. PEI preparation: The PEI part of the interview is very McKinsey-specific and distinct from other "fit interviews". Preparation with friends / peers / coaches who know the drill can be extremely helpful here.

Please feel free to reach out directly via DM to discuss how I can support you on short notice.

Cheers,
Kevin

Answer 2

Preparing for a case interview in just 7 days without prior live practice is tough, but absolutely doable. The key is focus, structure, and confidence.

Master the basics quickly – Review the main case types (profitability, growth, M&A, cost reduction, etc.) and keep a one-page “cheat sheet” of common structures. By day 3, you should be able to recall them naturally without notes.
Train your first-principles thinking – Remember, case problems are rarely rocket science; they’re often logical, real-world business questions. The interviewer wants to see how you structure, reason, and communicate clearly under time pressure.
Practice deliberately – Aim for ~3 cases a day (15–18 in total). Prioritize variety over volume—mix in both market sizing and qualitative reasoning, not just quant-heavy cases.
Excel or data-driven cases – Treat them like live analyst work: your logic, approach, and scenario thinking matter as much as the final number. Expect heavy calculations and comparisons. They may also watch how you react if the numbers are surprising or uncomfortable.
Mindset on the day – Go in calm, confident, and distraction-free. Be present in the conversation, listen actively, and keep your structure visible to the interviewer.

Answer 3

I'd do two things.

1. Try and move the interview. Postponing the interview is done by around 1/3 of candidates. It's not a big deal. The earlier you tell them the better. And the more time you manage to get, the better prepared you'll be for the interview.

2. Get a professional assessment / baselining case from a professional coach. You'll understand what you're good at (and how to turn it great) and where you struggle (and how to close the gap). You'll then work in a targeted way on the things that move the needle the most.

Best,
Cristian

Answer 4

Hello,

congrats for having been selected for the interviewes! Here some advice:

What is different in Excel cases

The thinking is the same. You still need structure, a clear hypothesis, and crisp communication.
The medium is different. You must translate that structure into a clean workbook, work fast with filters and pivots, and keep a running answer in words as you calculate.
The bar is consistency. Interviewers look for neat tabs, labeled outputs, and checks that catch mistakes before they do.

Day 1

Goal: Know the Excel case format and get your tools ready.

Watch two short case walk throughs or read two sample cases to refresh structure and synthesis.
In Excel, set up a clean template you will reuse
• Tabs Input, Work, Output
• Styles thousands separator on, percentage with one decimal
• Rows a header row that includes units and definitions
• A summary box at the top of Output with a one line answer and two supporting numbers
Drill the must know functions for cases for 45 minutes
• SUMIFS, AVERAGEIFS, XLOOKUP or INDEX MATCH, IF, COUNTIFS
• Pivot Table create, group by month or quarter, show values as percent of total
• Goal Seek for a breakeven or price to hit a target
Do one classic pen and paper case for 40 minutes. Focus on issue tree, math sanity checks, and a final one minute summary spoken out loud.

Deliverable a reusable Excel template with Input, Work, Output and a short written synthesis area.

Day 2

Goal: Read charts fast and calculate without getting stuck.

Do a 20 minute chart and exhibit drill. For each exhibit, say the headline in one sentence and write one implication.
Mental math circuit for 20 minutes
-Percent changes, weighted averages, growth rate approximations
-Two minute sets of 10 problems, then check and correct your method
Excel mini case number 1 for 45 minutes
Prompt You receive a transactions table with date, product, price, units, cost. Build revenue and gross margin by product, identify the top two drivers of margin change versus last quarter, and recommend one action.
Steps Clean headings, build a pivot for revenue and margin by product, calculate delta quarter over quarter, sort, write three bullet insights in Output.
Do one pen and paper case for 40 minutes. Record yourself and listen to the final minute for clarity.

Deliverable a one slide style Output tab with headline, two numbers, and one recommended action.

Day 3

Goal: Put it together under time. Identify gaps.

Timed Excel case for 60 minutes
• New dataset with two or three tabs
• Ask and write your clarifying questions as a short note in Output
• Build only what you need to answer the question
• End with three sentence synthesis
Review for 20 minutes. Check for formula mistakes, hard coded numbers, unclear labels.
Live coaching session 45 to 60 minutes
-Ten minute diagnostic on your structure
-Thirty minute Excel case walkthrough sharing screen
-Ten minute feedback and a personalized drill plan
Close with a 25 minute fit prep block. Draft two stories using the SCORE method Situation, Complication, Options, Resolution, Evidence.

Deliverable a list of three improvement targets for the next two days, for example slow with pivots, unclear final message, or messy workbook.

Day 4

Goal: Fix what Day 3 revealed, and sharpen your top down communication.

Targeted Excel drills for 60 minutes
-If lookup skills are weak, do 15 quick XLOOKUP or INDEX MATCH tasks
-If slicing data is slow, build three pivots and create a simple chart for each
-If quality control is weak, add a Checks section totals that reconcile to the raw data, and a reasonableness check against a hand calculation
Do one partner case for 45 minutes pen and paper or interviewer led. Emphasize signposting. Say where you are, what you will do next, what answer you expect to find.
Ten minute synthesis practice. Pick any dataset you built and write a two sentence CEO answer without numbers, then add two numbers that prove it.

Deliverable your Excel file now includes a small Checks box and a clearly labeled Output with headline first.

Day 5

Goal: Simulate the interview rhythm.

Pen and paper mock for 45 minutes. Time box math to keep momentum. Always round early, then refine if needed.
Excel case for 60 minutes. Force yourself to finish with a written answer even if analysis is incomplete. Interviewers value a clear message over a perfect model.
Ten minute debrief. What did you cut to finish on time. Write one rule you will apply tomorrow to decide what not to build.

Deliverable a one page prep log with strengths, gaps, and one rule to avoid overbuilding.

Day 6

Goal: Pressure test your readiness and polish your materials.

Live coaching session 45 to 60 minutes
-Full mock of an Excel case from brief to recommendation
-Real time feedback on keyboard use, formula choice, workbook hygiene, and synthesis
-Debrief with concrete next steps for your interview next week
Build your personal Excel case checklist for 20 minutes
-Clarify objective and unit of measure
-Create Input, Work, Output tabs
-Name ranges for key inputs
-Checks box totals and reasonableness
-Final headline and two proof points
Light fit practice for 20 minutes. Rehearse two stories out loud.

Deliverable your final checklist and a clean template you can recreate in minutes.

Day 7

Goal: Enter the interview fresh and confident.

Ten minute warm up. One exhibit, one percent change, one sanity check.
Thirty minute Excel mini case with smaller scope. Focus on speed and labeling.
Ten minute final review. Open your checklist and say each item out loud as if you are about to start the real case.
Rest, then prepare your space. Stable internet if remote, updated Excel, quiet background, calculator allowed or not, water nearby.

Deliverable a short readiness note to yourself what you will do in the first two minutes of the case, and how you will close.

Don't forget the standard prep

-Until the interview next week, split your time roughly sixty percent Excel, forty percent standard cases.
-After that interview and before McKinsey, flip it to forty percent Excel, sixty percent classic cases and fit.

Best of luck!