The Big 4 are Deloitte, PwC, EY and KPMG: the four largest global networks for audit, tax and consulting, and big players in IT consulting. If you searched "Big 4 tech companies" you may mean something else: Big Tech, usually Alphabet (Google), Amazon, Apple and Microsoft, often with Meta. This page covers the consulting firms and explains the difference.
Key takeaways
- The Big 4 consulting firms are Deloitte, PwC, EY and KPMG. "Big Tech" refers to technology companies such as Alphabet, Amazon, Apple, Microsoft and Meta.
- Deloitte is the largest by reported revenue: US$70.5 billion for the year to 31 May 2025.
- EY reported US$53.2 billion for the year to June 2025, of which Consulting was US$16.4 billion. KPMG reported US$39.8 billion for the year to 30 September 2025.
- Each is a network of legally separate member firms, not a single company. EY and KPMG, for example, are coordinated by UK-registered companies.
- If a Big 4 firm audits you, audit-independence rules limit the consulting it can sell you.
Big 4 tech companies or Big 4 consulting firms?
The two terms get mixed up because both groups are large and both sell technology. They are different kinds of business.
| Big 4 professional services firms | Big Tech companies | |
|---|---|---|
| Who | Deloitte, PwC, EY, KPMG | Usually Alphabet (Google), Amazon, Apple, Microsoft; often also Meta |
| What they sell | Audit, tax, advisory and consulting, including IT implementation | Software, devices, online services and cloud platforms |
| How they earn | Fees for people's time and managed services | Products, subscriptions, advertising and cloud usage |
| Structure | Networks of independent member firms | Listed companies with subsidiaries |
| Relationship | Big 4 firms are partners of the Big Tech cloud platforms (AWS, Microsoft Azure, Google Cloud) and implement them for clients. | |
So "Big 4 IT companies" can mean either group. In consulting and procurement conversations it nearly always means Deloitte, PwC, EY and KPMG.
In India there is a third meaning. "Big 4 IT companies" there often refers to the largest Indian IT services firms, usually named as TCS, Infosys, Wipro and HCLTech. They compete with the Big 4 consultancies for outsourcing and implementation work, but they are not audit firms. Our list of top IT services companies covers that group.
Who are the Big 4 firms?
All four started as accounting practices and grew through mergers into global networks. Today each runs a large consulting business next to its audit and tax work. The figures below come from each firm's own results release and are global.
Deloitte
Deloitte reported aggregate global revenue of US$70.5 billion for the fiscal year ending 31 May 2025, up 4.8% in local currency, and a workforce of over 470,000, according to its FY2025 revenue announcement. Its consulting is split into Strategy, Risk & Transactions and Technology & Transformation. Deloitte is often the default choice for very large ERP, cloud and AI programmes because of its delivery capacity.
PwC
PwC is organised around assurance, tax and advisory. Its technology consulting sits in advisory and leans towards finance, risk and regulated industries: ERP finance transformations, controls, cybersecurity and data. PwC publishes its global results in an annual review each autumn.
EY
EY reported global revenue of US$53.2 billion for the fiscal year ending June 2025, up 4.0% in local currency, per its FY25 revenue release. Consulting was the second-largest service line at US$16.4 billion, and EY-Parthenon, its strategy and transactions brand, was US$6.2 billion. The same release puts headcount at 406,209 at the end of June 2025.
KPMG
KPMG reported revenue of US$39.8 billion for the year ended 30 September 2025 on a continued operations basis, up 5.1% in local currency, with headcount of 276,030, according to its FY25 global revenue release. Advisory, which includes technology consulting, grew 2.9%, slower than tax and audit. KPMG is strong in regulatory, risk and financial services work.
How the Big 4 compare
| Firm | Latest reported revenue | Fiscal year end | People | Consulting brands |
|---|---|---|---|---|
| Deloitte | US$70.5bn | 31 May 2025 | Over 470,000 | Technology & Transformation; Strategy, Risk & Transactions |
| EY | US$53.2bn | June 2025 | 406,209 | EY Consulting; EY-Parthenon |
| KPMG | US$39.8bn | 30 Sep 2025 | 276,030 | KPMG Advisory |
| PwC | See PwC's Global Annual Review | – | – | PwC Advisory |
Revenue is for the whole network, including audit and tax, so it overstates the size of each consulting business. Of the releases cited here, only EY's breaks out a consulting revenue figure.
Where are the Big 4 from?
All four trace their roots to 19th- and early 20th-century accounting practices in the UK and the US. Today each operates as a network of legally separate member firms. The central coordinating entities are UK-registered in the cases we checked: EY's releases describe Ernst & Young Global Limited as "a UK company limited by guarantee", and KPMG International Limited is described as "a private English company limited by guarantee". These central entities do not serve clients themselves; local member firms do. That matters in practice: your contract is with the local firm, and quality and capacity vary by country.
How do the Big 4 differ from MBB?
MBB means McKinsey & Company, Boston Consulting Group and Bain & Company, the three best-known strategy firms. The differences are about scope rather than quality.
- Scope: MBB firms mostly advise on strategy and operating models. The Big 4 also implement systems and run managed services for years afterwards.
- Project length: MBB projects tend to be shorter and more senior-heavy. Big 4 technology programmes often run for months or years.
- Strategy arms: each Big 4 firm has built a strategy brand to compete with MBB, for example EY-Parthenon.
- Conflicts: MBB firms do not audit, so they carry no auditor-independence limits.
Are the Big 4 a good choice for IT and cloud projects?
They are a strong choice when the programme is large, cross-border and tied to finance, risk or regulation, and when you need one accountable firm for many workstreams. They are a weaker fit in three situations:
- They audit you. Independence rules restrict which non-audit services your auditor may provide, especially for listed and other public-interest companies in the EU.
- The work is mainly engineering. Cloud migration, platform engineering and 24/7 operations are often subcontracted to specialist partners anyway.
- You are mid-size. A smaller budget may get you a less experienced team. A specialist partner may put more senior engineers on the work.
Before you sign, ask who will do the work, which parts are subcontracted and what support looks like after go-live. For a broader comparison of large consultancies, see the top 5 IT consulting firms in the US.
How Opsio helps
Opsio is not a Big 4 firm. We are a cloud consultancy and managed service provider with offices in Karlstad, Sweden and Bangalore, India, and an AWS Advanced Tier Services Partner. Our work is the engineering end of IT consulting: cloud strategy, AWS migration and the operations that follow, for companies that want senior engineers rather than a large programme team.
For example, recruitment software company WorkBuster moved its global SaaS platform from a VMware-hosted MySQL setup to AWS with a near-zero downtime approach, using CloudFormation infrastructure as code and Multi-AZ MySQL on Amazon RDS. The details are in the WorkBuster case study.
Frequently asked questions
What are the Big 4 tech companies?
In technology news, "Big Tech" usually means Alphabet (Google), Amazon, Apple and Microsoft, often with Meta added. In consulting, the "Big 4" are Deloitte, PwC, EY and KPMG, which advise on and implement technology but do not make it.
Which Big 4 firm is the largest?
Deloitte, by reported revenue: US$70.5 billion for the year to 31 May 2025. EY reported US$53.2 billion for the year to June 2025 and KPMG US$39.8 billion for the year to 30 September 2025.
Which Big 4 firm is best for technology consulting?
There is no single answer. Deloitte has the largest delivery capacity, EY breaks out consulting revenue in its release (US$16.4 billion), and PwC and KPMG are often chosen for finance, risk and regulated-industry work. The team assigned to you matters more than the brand.
What country are the Big 4 from?
Their roots are in UK and US accounting firms, and their central coordinating entities, such as Ernst & Young Global Limited and KPMG International Limited, are UK companies limited by guarantee. Client work is done by local member firms in each country.
What are the Big 4 IT companies in India?
In India the phrase usually means the largest domestic IT services firms, commonly TCS, Infosys, Wipro and HCLTech. Deloitte, PwC, EY and KPMG also have large Indian member firms and delivery centres, which is why the two groups are often confused.
Is Accenture one of the Big 4?
No. Accenture is a listed technology services company and does not audit. It competes with the Big 4 in IT consulting and is often compared with them.
For hands-on delivery in India, see it consulting services.
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Written By
Country Manager, Sweden
Johan leads Opsio's Sweden operations, driving AI adoption, DevOps transformation, security strategy, and cloud solutioning for Nordic enterprises. With 12+ years in enterprise cloud infrastructure, he has delivered 200+ projects across AWS, Azure, and GCP — specialising in Well-Architected reviews, landing zone design, and multi-cloud strategy.
Editorial standards: This article was written by the cloud practitioner named in the byline above. We revise it when the technology or regulation it covers changes; the dates on this page show the latest update. Opsio maintains editorial independence.