Understanding the big three consulting firms — McKinsey, BCG, and Bain — is one of the quickest ways to signal preparation, analytical rigor, and cultural fit in interviews, sales pitches, and college conversations. This guide breaks down the history, cultural differences, typical interview expectations, common mistakes, and step-by-step prep tactics so you can use knowledge of the big three consulting firms to stand out.
What are the big three consulting firms and why do they matter in interviews
The big three consulting firms — often called MBB — are McKinsey & Company, Boston Consulting Group (BCG), and Bain & Company. Together they set the benchmark for strategy consulting, advising Fortune 500 companies, governments, and startups on high‑stakes decisions. Their prestige matters because interviewers and decision-makers use familiarity with the big three consulting firms as a proxy for your industry knowledge and fit with structured problem solving CaseBasix, I Got An Offer.
Quick essentials to remember about the big three consulting firms:
McKinsey: Founded 1926 by James O. McKinsey; largest by headcount and known for professionalism and deep industry practice teams BeaconFellows.
BCG: Founded 1963 by Bruce Henderson; celebrated for intellectual tools like the Growth‑Share Matrix and a strong focus on innovation and strategy CaseBasix.
Bain: Founded 1973 by Bill Bain (a former BCG partner); highly results- and implementation-oriented with strong private‑equity work and client ROI focus ManagementConsulted.
Referencing one of the big three consulting firms in a relevant way during an interview or pitch signals that you speak the structured-thinking language that these firms exemplify.
How do the big three consulting firms differ and what should you say about each one
Below is a compact comparison you can memorize and adapt to interviews, sales calls, or essays. Mentioning a specific differentiator shows you’ve done firm-specific research—an important prestige signal.
Firm | Founding Year & Founder | Size (approx) | Core Differentiator | Cultural/Expertise Focus |
|---|---|---|---|---|
McKinsey | 1926, James O. McKinsey | ~38,000 | Professionalism, industry depth [BeaconFellows][CaseBasix] | Values-driven, global scale |
BCG | 1963, Bruce Henderson | ~30,000 | Strategy tools (Growth‑Share Matrix) [CaseBasix][I Got An Offer] | Innovation, data-driven strategy |
Bain | 1973, Bill Bain | ~13,000 | Implementation, client results [ManagementConsulted] | People-focused, private equity expertise |
How to use this in conversation:
Job interview: “I’m drawn to McKinsey’s emphasis on industry depth and professionalism, which suits my structured leadership experience.”
Sales call with an MBB alum/client: “Like BCG’s Growth‑Share Matrix, I’d prioritize resource allocation across high-growth segments.”
College interview: “I’m inspired by Bain’s outcomes focus—at my internship I delivered a 20% productivity gain.”
Cite these differences when relevant to demonstrate nuanced, firm-specific knowledge CaseBasix, I Got An Offer, ManagementConsulted.
What common challenges do candidates face when discussing the big three consulting firms
Candidates often stumble in four predictable ways when the topic of the big three consulting firms comes up:
Overlooking prestige signaling: Failing to connect a firm‑specific point (e.g., BCG’s matrix) to your experience makes you sound underprepared [CaseBasix].
Giving generic answers: Interviewers at MBB expect MECE, structured explanations; vague stories don’t pass the threshold [I Got An Offer].
Cultural mismatch: Each of the big three consulting firms prizes different traits—McKinsey professionalism, BCG innovation, Bain results—so misaligned examples can hurt.
Case paralysis: The case style associated with the big three consulting firms is fast, structured, and quantitative; insufficient practice leads to lost time and poor synthesis.
Recognizing which of these you’re prone to is the first step to improving performance.
How should you prepare step by step using big three consulting firms as your guide
Use this practical checklist to prepare for interviews, pitches, or college conversations where the big three consulting firms are relevant.
Learn the basics (30–60 minutes)
Memorize founding years, founders, and one clear differentiator for each firm. These quick facts are conversation anchors [BeaconFellows], [CaseBasix].
Practice structured communication (2–4 hours/week)
Use MECE trees and issue trees to outline answers. Practice turning data into a 30‑second hypothesis and a one‑minute synthesis—MBB interviewers want crisp structure.
Do 20+ targeted case solves
Focus on profitability, market entry, and growth scenarios. Mimic the pace of the big three consulting firms’ case interviews by timing your problem structuring and math [I Got An Offer].
Tailor examples to culture
Prepare three STAR stories mapped to each of the big three consulting firms:
McKinsey story: leadership and professional impact.
BCG story: analytical rigor and creative problem solving.
Bain story: measurable results and implementation.
Role‑play firm‑specific scenarios
Run mock sales calls or interviews with peers and ask them to adopt an MBB evaluative posture. Use BCG frameworks or Bain ROI language in your pitch.
Signal fit early
Open with a one-liner that names the firm’s differentiator and links to your achievement: “I’m drawn to Bain’s results orientation—at X I improved Y by 20%.”
Update with current recruiting practices
Check Glassdoor, firm recruiting pages, and recent blogs for process changes and typical case formats [ManagementConsulted], [CaseBasix].
Do these steps repeatedly over several weeks and track progress with measurable targets (accuracy of math, synthesis time, number of frameworks used correctly).
How can Verve AI Copilot help you with big three consulting firms
Verve AI Interview Copilot can simulate MBB-style interviews and give targeted feedback on structure, timing, and language. Verve AI Interview Copilot provides live prompts to practice MECE issue trees and tracks how often you use firm-specific language like references to the Growth‑Share Matrix or Net Promoter Score. Verve AI Interview Copilot also runs mock case drills and gives remediation suggestions for your weakest areas. Try Verve AI Interview Copilot at https://vervecopilot.com for guided practice that mimics the pressure of real interviews.
What are common mistakes to avoid when referencing the big three consulting firms
Don’t confuse histories: Bain spun out from BCG origins—getting founders/dates wrong undermines credibility [BeaconFellows].
Don’t over-rely on jargon: Name‑dropping “MECE” or “NPS” without explaining their relevance looks superficial [CaseBasix].
Don’t neglect outcomes: If you praise Bain’s results focus, back it with quantified achievements.
Don’t overfit: If the interviewer isn’t MBB-focused, adapt and avoid forcing firm comparisons—use them only when they add clarity.
What are the most common questions about big three consulting firms
Q: What are the big three consulting firms
A: McKinsey, BCG, and Bain—elite strategy consultancies known as MBB [CaseBasix].
Q: Which firm is biggest among the big three consulting firms
A: McKinsey is the largest by headcount; BCG and Bain follow [BeaconFellows].
Q: How should I use the big three consulting firms in a job interview
A: Use a firm differentiator to frame your strength and provide a concrete, quantified example.
Q: Do the big three consulting firms all use the same interview style
A: All emphasize case interviews and structured thinking, but expectations and cultural emphasis vary.
Q: Is it risky to reference the big three consulting firms in non-consulting interviews
A: It can be useful for signaling structured thinking—use short, relevant references tied to your experience.
Q: How many practice cases should I do to prep like the big three consulting firms
A: Aim for 20+ practice cases, increasing difficulty and timing as you improve [I Got An Offer].
References and further reading
Overview of the big three consulting firms and their histories: A Brief History of MBB Consulting
Profiles and comparison of the big three consulting firms: CaseBasix Big 3 Firms
MBB-style case and interview resources: I Got An Offer — Big 3 Consulting Firms
Practical recruiting and interview tips referencing the big three consulting firms: Management Consulted — McKinsey Bain BCG
Final quick tip: Before any high‑stakes conversation, prepare a 20‑second opening that names one of the big three consulting firms and links a firm-specific trait to a concise personal example. That small move signals research, structure, and fit — the qualities interviewers want most.
