What Are the Big 4 Consulting Firms? A Complete 2025 Guide

What Are the Big 4 Consulting Firms? A Complete 2025 Guide

If you are new to consulting and keep hearing about the Big 4, you are in the right place. This guide gives you a clear, scannable definition, a simple Big 4 consulting firms list, and the answers to the questions people actually ask. No jargon. No fluff. Just what you need to understand the landscape and move forward with confidence.

The Big 4 in One Sentence

The Big 4 are the four largest global professional services networks that dominate audit and assurance, tax, and advisory work for companies and governments worldwide. They are Deloitte, PwC, EY, and KPMG.

The List: Who Are the Big 4 Firms?

What Do the Big 4 Actually Do?

The Big 4 grew from accounting roots, yet each now operates as a full professional services platform. Think of four major service lines that often work together on large client problems.

• Audit and Assurance: Independent reviews of financial statements and internal controls, including ESG and cybersecurity related reporting.
• Tax: Corporate tax strategy and compliance, transfer pricing, and support during reviews, increasingly data driven and automated.
• Advisory: Deals, risk, restructuring, and transaction support: due diligence, controls improvement, regulatory navigation.
• Consulting: Strategy execution and enterprise change: digital transformation, cloud migration, operating model, strategy cases, AI and data platforms, supply chain, and workforce transformation.

In short, the Big 4 help organizations measure performance accurately, comply with complex rules, and implement change at scale.

How Are the Big 4 Different from MBB?

MBB (McKinsey, Boston Consulting Group, and Bain) are best known for strategy consulting. The Big 4 do strategy too, yet their center of gravity is broader, combining assurance roots with end to end execution.

Want a deeper side by side? See our internal explainer: Big 4 vs. MBB comparison.

Big 4 Differences: What Actually Matters

The type of work is broadly similar across Deloitte, PwC, EY, and KPMG. What often differs: perception and local strengths.

• Perceived brand visibility: Deloitte is often most visible in consulting; perceptions vary by country, office, and practice.
• Local office and practice depth: Differences show up at the office and capability level; your experience depends on team and client portfolio.
• What to optimize for: Focus on practice quality, manager/partner fit, training path, and client exposure; ask about pipeline in the exact team.

Where caselane.ai Fits In

• Drill the essentials of structured problem solving and business math.
• Practice cases mirroring Big 4 advisory work: turnarounds, risk scenarios, tech change programs.
• Use AI driven feedback to close gaps quickly and build interview confidence.
• Launch our flagship course Crack the Case: free once you log in.

Ready to apply? Check the 2025–2026 consulting application deadlines.

ResumeLane and PeopleLane: Tools That Accelerate Outcomes

• ResumeLane: Professionally designed CV templates with AI grading that flags gaps, weak verbs, and missing metrics.
• PeopleLane: Networking intelligence to find people by firm, office, role, school, or deal type; build outreach lists and track responses.

Careers at the Big 4: Who Is a Good Fit?

• Type of work: In audit and tax: financial statements, controls, and regulations. In advisory and consulting: transformation programs across technology, operations, and data.
• Skills that stand out: Analytical thinking, data tools, clear communication, and appetite for learning; certifications like CPA, ACCA, CFA, and cloud/analytics help.
• Entry points: Campus analyst intakes, internships that convert to full time, experienced hiring, and graduate rotations.
• Culture and growth: Client facing early, frequent feedback, formal training, and mobility across teams; strong exits to industry.

Bottom Line

If someone asks you what are the Big 4 consulting firms, you can answer in seconds: Deloitte, PwC, EY, and KPMG. They started with accounting, now operate full-stack services, and help clients measure, comply, decide, and deliver.