CaseRound
L.E.K. interview prep · Updated Aug 2026

L.E.K. case interview: how to prepare (2026)

Market sizing shows up at L.E.K. far more often than at most firms, as a standalone question and buried inside longer cases. Here is how to make estimation a reflex instead of a stall.

The L.E.K. format
Candidate-ledTimed written caseDue diligence flavorMath-heavy
The short version
  • The cases are candidate-led. You open with a structure, ask for the data, and drive to a recommendation. Nobody hands you the next question, which is the single biggest difference from a McKinsey-style interview.
  • The written case is L.E.K.'s signature. Widely reported as roughly 60 minutes with a data packet, then a short deck presented to a panel. It usually sits in the final round, and L.E.K. publishes no details.
  • The math is heavier than average. Candidates consistently describe real numbers, dense tables, and multi-step arithmetic rather than tidy round figures.
  • Commercial due diligence and life sciences run through everything. Case content leans toward the firm's actual work: is this market attractive, should this investor buy this asset, will this drug sell.
  • The fastest thing you can do today: say a full structure out loud within 90 seconds of hearing a prompt, then keep driving without being invited.
Start a free voice mock interviewSee pricing

Live voice interview with real follow-up questions, scored on 8 dimensions. Your first one is free, no card needed.

On this page

L.E.K. interview at a glance

Stage or element What to expect
Case format Candidate-led. You structure, ask for data, and drive to the recommendation
Rounds Commonly two, with two to three interviews in each. L.E.K. says the process "differs slightly by region" and by level
Interview length Reported between 30 and 60 minutes, usually mixing a short fit section with a case
Screening An online test for many candidates. Reports split between a numerical reasoning test and a short game-based assessment, and it varies by office
Signature element A timed written case, most often in the final round, presented to a panel
Typical cases Market sizing, market attractiveness, growth, profitability, and commercial due diligence
Sector flavor Life sciences and healthcare, private equity, consumer, industrials

What makes the L.E.K. case interview different?

You drive the whole thing. L.E.K. cases are candidate-led by broad agreement across prep sources. That means no interviewer handing you the next branch, no rescue if you stall, and no partial credit for a good framework you never used. L.E.K.'s own guidance tells candidates to "stick to your approach" and work "point-by-point," which is only possible if the approach was yours to begin with.

The numbers are real numbers. Candidates consistently describe L.E.K. math as heavier than average: dense tables, several steps chained together, and figures that do not round conveniently. The arithmetic is not exotic. The pressure comes from doing it while narrating, without going silent for 40 seconds.

Evidence beats opinion. L.E.K.'s recruiting page asks candidates to bring "your intellectual curiosity, your analytical mind and your appetite for evidence." In practice that means a recommendation with no number behind it lands badly here, even when the logic is fine.

The work shows up in the cases. L.E.K. describes its due diligence practice as providing "independent, fact-based analysis" so investors can select "the right opportunities" while "avoiding surprises." That is close to a job description for the cases too. You are frequently being asked whether something is worth buying, entering, or backing.

How does the L.E.K. interview process work?

1
Application.L.E.K.'s careers site says it reviews "every application submitted" and that selected candidates are "invited to attend several rounds of interviews."
2
An online test, for many candidates.L.E.K. does not publish a format. Its own London recruiting blog describes a process of "multiple rounds, including online testing and face-to-face interviews," with online testing that "included psychometric and math exams." More on what candidates report below.
3
First round.By most accounts two interviews, each pairing a short fit conversation with a case. An L.E.K. associate writing on the firm's own blog described a Boston first round of "two interviews, one focusing on case strategy and one that was more quantitative," which matches how prep sources describe the split.
4
Final round.Two to three interviews with principals and partners, and in many processes the written case. Some offices run both rounds as a single day. Others space them out. Your invitation email is the only reliable schedule.
5
Decision.L.E.K. publishes no timeline. Candidate reports on Glassdoor put the average process at around three weeks, with wide variation by office and level.

The honest caveat is one L.E.K. states itself: "The interview process differs slightly by region and depends on the level for which you're applying." Any guide that gives you one universal L.E.K. schedule, including the ranges above, is describing a pattern rather than your process.

What is the L.E.K. written case?

This is the part candidates ask about most, and the part L.E.K. publishes nothing about. Everything below is candidate-reported, so treat it as a pattern rather than a promise.

The consistent shape across prep sources: you get a packet of data, roughly an hour to work through it alone, and then you present a short deck to a panel and take questions. Reports commonly describe about 20 minutes of presentation followed by about 10 minutes of Q&A. It usually appears in the final round, alongside two live cases.

The details are exactly where sources stop agreeing. Packet size is reported anywhere from 15 to 50 pages. Output is described as roughly 7 to 10 slides. Some accounts describe three specific questions to answer, others a single open brief. That spread is a real signal, not sloppy writing: the exercise varies by office and level, so build the skill rather than memorizing one version.

Four things travel across every version:

1
You cannot read the whole packet, and you are not supposed to.The exercise is a triage test. Find the three or four exhibits that decide the answer and leave the rest.
2
Headlines carry the argument.A slide titled "Market growth" says nothing. "Growth is concentrated in one segment we do not serve" is a finding. This is the habit that separates strong decks from decorated ones.
3
Commit to an answer.A deck that lists considerations without recommending anything reads as unfinished, and the Q&A will find that out in about 30 seconds.
4
Defend it under questioning.The panel pushes. Knowing which number your recommendation rests on, and what would change your mind, is the whole test.

One honest limit before you build a study plan around it: no voice tool trains this, ours included. Building slides under a clock is a different muscle from talking, and it needs a real deck, a real timer, and ideally a person to present to.

What is the L.E.K. online assessment?

L.E.K. does not publish what it sends you, and candidate reports split into two clearly different experiences.

Some describe a numerical reasoning test: a conventional data-and-questions format under time pressure, sometimes proctored. Others describe a short game-based assessment, commonly reported at around 10 minutes, mixing quick mental math, pattern recall, and a logic puzzle. L.E.K.'s own London blog refers simply to "psychometric and math exams," which is compatible with both.

Two practical implications. Read your invitation email carefully, because it names your assessment and generic guides get this wrong constantly. And warm up the underlying skills, which are the same ones the cases test: fast percentages, reading a table without panicking, and staying calm on a clock. No tool prepares you for the assessment itself, ours included.

What does an L.E.K. case sound like?

InterviewerOur client is a private equity fund looking at a company that runs outpatient dialysis clinics in one European country. They want to know whether the market is attractive enough to bid. Where would you like to start?
CandidateTwo clarifying questions first. Is the fund evaluating this as a growth story or a cash generator? And is reimbursement in this country set nationally or by region?
InterviewerGrowth story. Reimbursement is national, and it has been flat in nominal terms for four years.
CandidateThat shapes the structure. I would look at three things in order. First, volume growth, which for dialysis is driven mostly by disease prevalence and by how many patients get treated at home instead. Second, price, which sounds capped, so real revenue per session is eroding with inflation. Third, competition and site density, since clinics are a local-catchment business. I would start with volume, because if patient volume is not growing, flat reimbursement makes this a declining business in real terms.
InterviewerPrevalence is growing about two percent a year, and home dialysis has gone from four to nine percent of patients in five years. What do you make of that?
CandidateNet, in-clinic volume is roughly flat. Prevalence adds about two points a year and home dialysis has been taking about one point of share a year, so clinic demand grows maybe one percent while the price per session falls in real terms. That points away from a growth story. Before I conclude, I would want to know whether home dialysis adoption is still accelerating, because that trend line decides whether this is flat or shrinking.

Notice the rhythm. Clarify, commit to an order and say why, then convert the data into a directional answer instead of narrating it back. Nobody prompted the candidate to draw a conclusion. That is what candidate-led means, and it is trainable, but only out loud.

Train the candidate-led rhythm out loud.

A live voice interviewer probes your answers, hands you exhibits mid-conversation, and scores the interview on 8 dimensions. Your first full interview is free, no card needed.

Run a candidate-led voice mockNo credit card required
What a CaseRound mock gives you
  • A live voice interviewer who probes your answers, out loud
  • Candidate-led mode, the format L.E.K. cases use
  • Exhibits handed to you mid-conversation, like in the room
  • A score on 8 dimensions plus the full transcript to review
  • Our case library, plus any casebook PDF you upload (Sprint and above)

Not covered, and no voice tool covers it: the written case. Building a deck under a clock and defending it to a panel needs slides, a timer, and a person. The online assessment and behavioral probing are outside what we train too, and we do not have L.E.K.'s own cases.

Which case types does L.E.K. run?

  • Commercial due diligence. The house specialty. "An investor is looking at this company. Is the market attractive, is the company's position defensible, and does the growth plan hold up?" Structure it around market, competition, and the plan itself, not around a generic profitability tree.
  • Market sizing. Reported far more often at L.E.K. than at most firms, both as a standalone question and inside a larger case. L.E.K.'s own published Large Pharma Co. case asks candidates to size the market for a baldness cure and then price it.
  • Life sciences and healthcare. Drug launches, payer coverage, medtech adoption, provider economics. Sector vocabulary matters here. Knowing what reimbursement, formulary access, and a patent cliff are will save you several minutes you do not have.
  • Growth and market entry. "Where should this business grow next, and what would it take to win there?"
  • Profitability. L.E.K.'s own published Brewery Profits case is one of these: two competing beer brands with similar revenue, one with steady profits and one with swings, and you have to explain why.

If your structuring still leans on memorized frameworks, read why memorized frameworks fail before drilling case types. Candidate-led interviews punish borrowed structures faster than any other format, because you have to use the thing you just drew.

What does a strong L.E.K. answer sound like?

Same prompt, two answers. The interviewer says: "The target's revenue grew nine percent last year while the overall market grew three percent. What does that tell you?"

A weak answer restates the number:

Weak answerSo they grew faster than the market, which is good. That suggests they are winning share and the business is performing well.

A strong answer asks what kind of growth it was:

Strong answerThey took about six points of share, so the first question is how. Three possibilities, and they are worth very different multiples. If it came from price, that is the most durable and I would want price per unit over time. If it came from volume in existing accounts, that is solid but eventually caps out. If it came from discounting or from one large contract win, it is much weaker and may not repeat. I would ask for revenue growth split into price and volume, and for customer concentration, because a single contract behind that six points changes the recommendation.

Almost the same information. The second answer treats the number as a question rather than a verdict, names what would change the conclusion, and asks for one specific data set. In a due diligence flavored case, that is the difference between passing and not.

What do L.E.K. interviewers score?

L.E.K. publishes no rubric, and any specific weighting you find online is invented. What prep sources agree on, and what lines up with the firm's own language, is four things: structure, quantitative accuracy, business judgment, and communication.

Two are worth calling out because L.E.K. leans on them harder than average. Quantitative accuracy carries more weight here, since the math is denser and a wrong number often carries straight into the recommendation. And synthesis is the most commonly reported failure mode: candidates who do every step correctly and never say what it all means. L.E.K.'s own advice is to "come up with an answer" while showing flexibility, which is a polite way of saying that hedging is not a strategy.

So score yourself on those dimensions instead of counting completed cases. A CaseRound mock scores every interview on 8 dimensions, including structure, math, judgment, synthesis, and communication, and returns the full transcript so you can see exactly where a branch went wrong.

How should you practice for L.E.K.?

1
Drill the candidate-led opening.Hear a prompt, ask two clarifying questions, deliver a structure in 60 to 90 seconds, then keep driving without being invited. Out loud. Reading structures builds recognition, not delivery, and recognition is not what gets tested.
2
Do math while talking.Not silently on paper. Set a table of ugly numbers in front of you and narrate the calculation. The failure mode at L.E.K. is not getting it wrong, it is going quiet for a minute and killing the conversation.
3
Learn the sector vocabulary.A weekend on how drug pricing, payers, and provider reimbursement work removes the single most common stall in an L.E.K. life sciences case.
4
Practice the written case separately.Take any dense industry report, give yourself 60 minutes, and produce seven slides with argued headlines plus a recommendation. Then present it to someone for 20 minutes and let them push back. This is the part that needs a person and a deck, not a voice tool.

Save your scarce person-time for the written case and fit stories. The live case reps are the part you can run nightly.

Where can you find official L.E.K. prep resources?

L.E.K.'s careers site publishes its own interview preparation page, and it is the most reliable thing you will read on this topic because it comes from the firm. It states plainly that "we use case-based interviews so we can see how you approach specific business problems, marshalling data and your own experiences to reach and defend a conclusion," and it gives seven in-case tips including take your time, ask questions to clarify scope, formulate hypotheses, share your thought process, and come up with an answer.

As of our August 2026 check, the page also carries three worked practice cases: an airplane brainteaser, Brewery Profits, and a Large Pharma Co. sizing and pricing case. Use them actively rather than reading the solutions. Reading a solved case teaches you what a good answer looks like. Running the same case out loud, with something probing your answers, teaches you to produce one. You can do that on CaseRound too: upload a case PDF and run it as a live voice interview (Sprint and above). One thing we do not have and will not claim: L.E.K.'s own cases. Comparing tools? See how CaseRound compares.

L.E.K. vs. Bain and EY-Parthenon

L.E.K. Bain EY-Parthenon
Who leads the case Candidate Candidate Candidate
Signature element Timed written case in many finals Experience interview and PE flavored cases Strategy cases inside a Big Four process
Screening Online test, format varies by office SOVA or TestGorilla by office Online assessment, varies by country
Case flavor Due diligence, life sciences, market sizing Private equity and performance improvement Transaction and growth strategy
Math intensity Heavier than average Moderate Moderate to heavy

What happens after the final round?

L.E.K. publishes no timeline and no acceptance rate, so treat every number you read online, including the ones here, as directional. Candidate reports on Glassdoor put the average process at roughly three weeks from first contact to decision, and final-round outcomes are commonly reported within one to two weeks. Campus processes tied to a cohort start date run longer than experienced-hire ones.

On reapplication, L.E.K. states nothing public. Cooling-off periods reported by candidates vary by office, so ask your recruiter rather than assuming a rule that may not exist where you applied. If you got to the written case and did not convert, that is worth saying out loud in a reapplication, because reaching it at all means the live cases went well.

Your interview week checklist

  • A 60 to 90 second structure, out loud, for market attractiveness, market entry, profitability, and a due diligence prompt
  • One full market sizing done aloud daily, ending with a sanity check on your own number
  • Mental math with ugly numbers, narrated, not silent
  • One timed written case rehearsal: 60 minutes of analysis, seven slides with argued headlines, 20 minutes presenting to a person
  • Basic life sciences vocabulary: reimbursement, payer, formulary access, patent cliff, phase two versus phase three
  • At least three full candidate-led voice mocks where you drive from the opening question to the recommendation

Interview this week? One full mock today will do more than another evening of reading. The first one is free, and Sprint covers 30 sessions for $39.

Frequently asked questions

Is the L.E.K. case interview candidate-led or interviewer-led?

Candidate-led, by broad agreement across prep sources. You structure the problem, ask for the data you want, and drive to a recommendation without being prompted. Some interviewers steer more than others, so practice leading and being redirected rather than assuming a single script.

Does every L.E.K. candidate get a written case?

No, and L.E.K. publishes nothing about it. It is widely reported in final rounds, especially for associate and consultant level roles, but the format varies by office and level and some processes do not include one. Your invitation email or recruiter is the only reliable answer.

How long is the L.E.K. written case?

Most reports put it at around 60 minutes of analysis followed by a presentation of roughly 20 minutes plus about 10 minutes of questions. Packet size is reported anywhere from 15 to 50 pages and output at roughly 7 to 10 slides. Prepare for the shape rather than a specific page count.

How hard is L.E.K. math compared to other firms?

Heavier than average. Candidates consistently describe dense tables, multi-step calculations, and numbers that do not round neatly. The arithmetic itself is standard. What is tested is whether you can keep talking while doing it and state your assumptions instead of hiding them.

What sectors do L.E.K. cases cover?

Cases track the firm's real work, which is concentrated in life sciences and healthcare, private equity and commercial due diligence, consumer, and industrials. Sector vocabulary is worth a weekend. Asking what formulary access means mid-case costs you time you do not have.

Does L.E.K. have an online assessment?

Many candidates get one, and reports describe two different experiences: a numerical reasoning test, or a short game-based assessment of around 10 minutes. L.E.K.'s own London recruiting blog refers to "psychometric and math exams." It varies by office and cycle, so check your invitation and do not assume the version a friend in another country described.

Can you practice the written case with a tool?

Not with a voice tool, ours included. The written case tests triage, slide-building under a clock, and defending a deck to a panel. That needs a real timer, real slides, and a person to present to. What a voice tool trains well is the live case half, which is three of the four or five interviews in a typical L.E.K. process.

Is the free CaseRound mock candidate-led?

Not currently. The free starter case runs interviewer-led so you experience the live voice interviewer and the scored feedback end to end. Candidate-led cases sit in the full library on Sprint and above, and that is the mode to drill for L.E.K.

How long should you prepare for L.E.K.?

Most candidates describe four to six weeks of focused preparation. If your interview is sooner, prioritize live practice over reading, and spend one of those sessions on a timed written-case rehearsal. One full mock exposes more gaps than a weekend of theory.

Your next interview should not be the real one.

Run a full candidate-led voice mock: live follow-up questions, exhibits in the conversation, scored feedback on 8 dimensions, and the full transcript to review. The first one is free, no card. Interviewing this month? Sprint is $39 for 30 sessions, no subscription.

Start a free voice mock interviewNo credit card required

Train the skill behind the case

TechniqueCase interview math: explain before you calculateInterviewers grade the setup more than the arithmetic, and they still expect the arithmetic...TechniqueHow to present your case interview structure (word for word)The first minutes after the interviewer asks how you would approach it decide more than any...TechniqueThe 10 most common case interview mistakes (and what to do instead)The same ten mistakes cost candidates offers every season, and interviewers are trained to...All guidesBrowse every guide13 guides on structure, math, sizing and the rest

Also interviewing elsewhere?

Firm guideEY-Parthenon case interviewCandidate-led · PE and CDD casesFirm guideBain case interviewCandidate-led · Experience interviewFirm guideOliver Wyman case interviewCandidate-led · Math-heavy casesAll firmsSee every firm guide30 firms, same format, one list

CaseRound is an independent interview prep platform and is not affiliated with, sponsored by, or endorsed by L.E.K. Consulting.