Of the three practice cases on L.E.K.'s interview preparation page, two open with an estimate. Candidates who treat that estimate as a warmup spend the rest of the hour defending a denominator they never pressure-tested.
That is the thesis of this guide. L.E.K. is candidate-led in the material it publishes, but the firm is not "BCG with a different logo." The estimate is usually the frame for pricing, investment, or go/no-go. The six tips L.E.K. lists for live interviews are closer to a scoring sheet than to motivational fluff. After this piece you should be able to map your invitation against what the firm confirms publicly, run a sizing that survives a sensitivity, and know what belongs in practice versus folklore.
This article is the process and scoring guide. Worked walkthroughs of L.E.K.'s three published prompts live on the sibling practice cases page.
What L.E.K. confirms about the process
L.E.K. Consulting is a global strategy firm with 27 offices as of a May 2026 firm announcement. Its public work sits heavily in growth strategy, M&A support, and private equity commercial diligence — L.E.K. states PE clients engage it on more than 400 projects a year. Life sciences, MedTech, consumer, and industrials show up often in the firm's industry pages. That mix shows up in interviews as indication math, patient or procedure funnels, and diligence-style sizing more often than a generic "profit is down" tree.
The Apply page is the only process statement that binds every office:
| Element | What L.E.K. states | How to treat it |
|---|---|---|
| Application review | Every application is reviewed | Invitation, not folklore, sets the sequence |
| Rounds | Several rounds | Expect more than one stage |
| Interview mix | Experiential and case interviews | Fit stories plus cases in the same process |
| Case types | Quantitative or strategic | Do not prep only one flavour |
| Regional variation | Differs slightly by region and level | London is not Boston; follow your pack |
| Office choice | One global office application per year | Pick the office before you click apply |
Nothing on that page fixes a universal online test, a fixed round count, or a written case for every candidate. Those appear in some regions and levels. Treat candidate reports as hypotheses until your invitation confirms them.
The six tips are the scoring sheet
L.E.K. publishes six behaviours for the live case. Read them as what the interviewer is marking, not as soft advice.
| Tip (L.E.K.'s words, shortened) | What I listen for in the room |
|---|---|
| Take your time; restate facts and assumptions | You heard the decision, not just the industry |
| Gather thoughts; form questions and an approach | A coherent first tree before you grab a calculator |
| Stick to the approach | Methodical progress, not topic-hopping |
| Ask questions | You request the highest-leverage data, not trivia |
| Formulate hypotheses aloud | Transparent updates as exhibits arrive |
| Come up with an answer; stay willing to rethink | A recommendation that can move when the math moves |
Tip six is the one most candidates miss. They either never commit, or they glue themselves to the first number. In a typical first-round set of two cases, I would rather see a clean wrong number that you correct after a check than a floating "it depends" that never lands.
Ned's rule. If a ±20% swing in your opening estimate flips the recommendation and you have not said so out loud, you have not finished the case. You have only finished the arithmetic.
What the three published cases signal
L.E.K. puts three prompts on the careers site and withholds answers. Under each prompt it asks the same meta-questions: clarifying questions, what you know, how you would organize, what data you need, what assumptions you would make. For the aircraft brainteaser it also asks which logical traps to avoid.
| Published case | Job it is testing | Estimate required? |
|---|---|---|
| Aircraft brainteaser (JFK–LAX passers) | Clarifying questions and trap awareness | Yes — a count under constraints |
| Brewery profits (Cheapo vs Bourgeois) | Driver diagnosis and a CEO action plan | Mostly qualitative, then structured fixes |
| Large Pharma Co. (IPP2 baldness pill) | Market size plus pricing logic | Yes — size, then price |
Two of three force an estimate. That is not subtle. L.E.K. is telling you that opaque "framework theatre" without a denominator will not carry the hour. Decode the prompts end to end on L.E.K. practice cases; this guide stays on process and scoring.
Regional process: invitation beats the internet
Official employee interviews on lek.com show how far offices can diverge while still matching the Apply-page language.
London (Associate), per Tom Adams (2023). Multiple rounds including online psychometric and math tests, then face-to-face case and fit interviews. Adams stresses structured problem-solving over a single "right" answer, and recounts a wedding market-sizing where the methodology was sound but the double-count of partners was not — and the interviewer cared that he caught it.
Boston (Associate), per Teddy Simson (2022). First round: two interviews, one more strategic and one more quantitative, plus background and behavioural questions. Later stage: partners and principals, still mixing quant and behavioural. No online test is named in that write-up.
Folklore online often freezes those stories into a universal pipeline ("everyone gets a 60-minute written case" or "everyone sits SHL"). L.E.K. does not publish that rule. If your invitation names a written case, rehearse a timed packet and a short slide-style recommendation. If it does not, spend the hours on live cases and sizing instead.
Titles before you compare offers
On L.E.K.'s roles page, Associate is the undergraduate full-time title and Consultant is the post-MBA title that manages the case team day to day. Summer Associate and Summer Consultant mirror those tracks. PhD Analyst and Life Sciences Specialist are separate advanced-degree paths with heavier analytical and scientific workstreams. McKinsey's "Associate" is the MBA hire. Ignore the shared word; check the base and the role description for the office you applied to.
Worked example: estimate as the price constraint
Invented prompt, L.E.K.-shaped. Reproduce the arithmetic on paper.
Prompt. A PE client is diligencing NorthGrid Coatings, which sells industrial floor coatings to US warehouses over 50,000 sq ft. There are 95,000 such sites. Average floor area is 80,000 sq ft. Incumbent coatings last five years at $1.80 per sq ft. NorthGrid's formula lasts seven years. Facilities managers will switch only if annualized coating cost rises by no more than 10%. What is the maximum price per sq ft NorthGrid can charge, and is a 12% share of annual recoats enough to fund a $3.0 million dedicated sales team if COGS is $0.90 per sq ft?
Clarify. Is the 10% measured versus the incumbent's annualized cost, or versus cash outlay in the purchase year? Assume annualized. Geography: US only. Switching: all-or-nothing at the site level.
Structure. (1) Incumbent annualized cost per site. (2) Max annualized for NorthGrid. (3) Max price given seven-year life. (4) Annual recoat pool and revenue at 12% share. (5) Contribution versus sales cost.
Math.
Incumbent annualized cost per site:
80,000 × $1.80 / 5 = $28,800 per year.
Max annualized under the 10% rule:
$28,800 × 1.10 = $31,680 per year.
Max NorthGrid price:
$31,680 × 7 / 80,000 = $2.77 per sq ft.
Status-quo recoat pool each year (five-year cycle):
95,000 / 5 = 19,000 sites → 19,000 × 80,000 = 1.52 billion sq ft.
At 12% share and $2.70 per sq ft (slightly under the ceiling):
Revenue ≈ 1.52B × 0.12 × $2.70 ≈ $492 million.
Contribution at $0.90 COGS:
($2.70 − $0.90) × 1.52B × 0.12 ≈ $328 million.
The $3.0 million sales team is trivial against that contribution. The live question is not "can we afford sales?" It is "can we win 12% at a ~54% price premium to the incumbent's $1.80 while still clearing the annualized budget rule?"
Sensitivity (Ned's rule). If durability is only 6 years, not 7, max price falls to $31,680 × 6 / 80,000 = $2.38. Premium shrinks; win rate assumptions should move with it. Say that out loud before you recommend a bid.
Recommendation. Price at $2.60–$2.70 with a durability guarantee in the contract. Underwrite the deal only if primary research with 20–30 facilities managers supports double-digit share at that premium. Risk: the 10% annualized rule is a talking point, not a formal budget policy. Next step: confirm how buyers actually measure cost.
That is the L.E.K. shape: the estimate sets the price ceiling, and the ceiling sets the diligence call.
Experiential interviews are not a soft second act
The Apply page lists experiential interviews alongside cases. L.E.K.'s stated objectives include motivation for consulting and for L.E.K. specifically, plus evidence of how you think on business issues. Official associate interviews mention storytelling prompts and partner-level behavioural questions that may not look like textbook PEI. Prepare three or four specific stories — leadership, conflict, failure, impact — and a crisp "why L.E.K." that names real work (PE diligence cadence, life sciences depth, apprenticeship model) rather than a generic strategy pitch. Rehearse follow-ups on behavioral.
Practice this week
- Open L.E.K.'s interview preparation page. Cold-outline all three published cases using their own approaching questions. Do not peek at third-party writeups first.
- Run one market-sizing drill to a recommendation with a ±20% sensitivity spoken aloud.
- Do a five-minute first rep on /start (three typed turns, instant scores, no account), then one full voice case on /interview if you want the timed debrief.
- If your invitation names a written case, time a 45–60 minute packet with a one-page recommendation. If it does not, spend those hours on live cases instead.
Everything on CoachNed is open for seven days with no card; then $120 for a recruiting season or $49 a month. CoachNed is independent and not affiliated with L.E.K. Consulting.
Frequently asked questions
Is the L.E.K. case interview candidate-led or interviewer-led?
Candidate-led in the material L.E.K. publishes: you restate the problem, build an approach, ask for data, and commit to an answer. Confirm live with your interviewer; some offices or seniors run a more guided style without renaming the format.
Does every L.E.K. candidate take an online test?
No. L.E.K.'s Apply page does not mandate a global online screen. A London Associate process described on the firm's careers blog included psychometric and math tests; other official writeups do not mention them. Follow the invitation.
Is there always a written case at L.E.K.?
No. Written cases appear in some finals by region and level. They are candidate-reported, not a firm-wide rule on the Apply page. Prep one only when your materials name it.
What is an L.E.K. Associate versus a Consultant?
Associate is the undergraduate full-time title; Consultant is the post-MBA title that runs the case team day to day, per L.E.K.'s roles page. Do not map either word onto McKinsey titles.
How should I use L.E.K.'s three practice cases?
Treat the prompts and the "approaching the case" questions as the exercise. The firm publishes no answers. Work them cold, then compare your approach to a structured debrief — the sibling practice-cases article walks each prompt without claiming to be official answers.
Sources
- Interview Preparation | L.E.K. Consulting — six live-interview tips and three official practice cases (aircraft, brewery, Large Pharma Co.). Checked 2026-09-24.
- Apply | L.E.K. Consulting — process differs by region and level; mixture of experiential and quantitative/strategic case interviews; one office application per year. Checked 2026-09-24.
- The London L.E.K. Interview Process with Tom Adams — London Associate path with online psychometric/math tests and case/fit interviews (2023). Checked 2026-09-24.
- L.E.K. Interview Process with Teddy Simson — Boston Associate first-round split (strategy vs quantitative) and partner/principal finals (2022). Checked 2026-09-24.
- Roles at L.E.K. — Associate vs Consultant, summer tracks, PhD Analyst, Life Sciences Specialist. Checked 2026-09-24.
- Private Equity Consulting | L.E.K. Consulting — PE work across the deal cycle; more than 400 PE projects per year. Checked 2026-09-24.
- L.E.K. press release on Asia-Pacific Life Sciences partner — firm operates across 27 offices worldwide (May 2026). Checked 2026-09-24.