UK SME Size Breakdown 2025: Micro, Small, Medium, Large Business Statistics

UK business size stats can look messy until you line up the definitions and the time periods. Using the latest official business population snapshot for the start of 2025, the UK had 5.7 million private sector businesses, and almost all of them were SMEs. Small businesses (0 to 49 employees) made up 99.18% of the total, medium-sized businesses (50 to 249) were 0.67%, and large businesses (250+) were 0.15%. The total business population was also up 3.5% versus 2024 (an increase of 191,000 businesses). Business population estimates for the UK and regions 2025 (statistical release)

What counts as micro, small, medium and large in UK statistics?

• Micro: usually 0 to 9 employees. In the business population release, “micro” is shown as 1 to 9 employees, with “non-employers” broken out separately.
• Small: 10 to 49 employees (sometimes “small businesses” are reported as 0 to 49, which includes non-employers and micro).
• Medium: 50 to 249 employees.
• Large: 250 or more employees.

One detail that trips people up, “with no employees” is not “no work”. It includes self-employed owner-managers, and also companies with one employee that are treated as a working proprietor in this series.

UK business counts by size at the start of 2025

Here is the cleanest size breakdown for day-to-day use. It shows counts, plus employment and turnover for each band. (Employment is shown in thousands, turnover is shown in £ millions.)

Business size band	Businesses	Employment (thousands)	Turnover (£m)
With no employees	4,272,535	4,664	402,611
Micro (1 to 9 employees)	1,150,875	4,156	701,248
Small (10 to 49 employees)	220,085	4,324	776,163
Medium (50 to 249 employees)	38,435	3,738	948,639
Large (250+ employees)	8,335	11,246	2,696,001
All private sector businesses	5,690,265	28,128	5,524,662

Quick read of what this table means

• Most UK businesses are tiny. About three quarters have no employees, and the UK also has well over a million micro employers (1 to 9 employees).
• Large businesses are rare, but economically heavyweight. Only 8,335 businesses had 250+ employees, yet large firms accounted for 11.2 million of the 28.1 million total private sector employment in this snapshot, and £2.7 trillion of the £5.5 trillion turnover shown (turnover excludes financial and insurance activities in this series).
• SMEs are almost the entire population. SMEs (0 to 249 employees) accounted for 99.85% of businesses, 60% of employment, and 51% of turnover in the same snapshot.

Employment and turnover by size, the “why it matters” view

For planning, the most useful split is often “who employs people” and “who drives turnover”. In this series, at the start of 2025:

• SMEs: 16.9 million employment (60% of total), £2.8 trillion turnover (51%).
• Small businesses (0 to 49): 13.1 million employment (47%), £1.9 trillion turnover (34%).
• Medium-sized businesses (50 to 249): 3.7 million employment (13%), £0.9 trillion turnover (17%).
• Large businesses (250+): 11.2 million employment (40%), £2.7 trillion turnover (49%).

This pattern is why UK “SME strategy” often needs two tracks: a micro and small track (huge numbers of firms, distributed demand) and a medium-plus track (fewer firms, but bigger operational footprints and budgets).

How the UK size mix has changed since 2010

The long-run story is not “more large businesses”. It is “more non-employers”. Since 2010, the growth in the business population has mainly come from non-employing businesses, with non-employers up by 1.014 million (31%) and employing businesses up by 193,000 (16%). Non-employers accounted for 84% of total business growth over that period.

Why your Companies House count will not match SME counts

If you are looking at Companies House totals and wondering why the numbers do not line up with “UK businesses”, you are not alone. You are comparing different universes:

• Business population estimates cover the UK private sector business population, including many unincorporated businesses.
• Companies House covers incorporated entities on the company register, and reports on register size, incorporations, dissolutions, and related activity.

For example, Companies House reported that the total register size at the end of the financial year ending 2025 (31 March 2025) was 5,427,787, up 1.4% versus the prior year. During that year there were 801,864 incorporations (down 10.0%) and 726,735 dissolutions (up 9.6%). Companies register activities April 2024 to March 2025 (Companies House)

There is also a quality and compliance angle. In its 2024 to 2025 annual report, Companies House said it queried or removed false, misleading, or inaccurate register information relating to 106,300 companies between 1 April 2024 and 31 March 2025. Companies House annual report and accounts 2024 to 2025

How to use these stats for 2026 market sizing and planning

1) Pick the right unit: “businesses” vs “companies” vs “registered businesses”

• If you sell to owner-managed firms, “business population” is usually the best top-of-funnel universe.
• If you target limited companies only, Companies House is often the sharper lens.
• If you need financial performance by sector, the ONS Annual Business Survey is the common reference point, but pay attention to revisions and corrections for the latest year.

On that last point, the ONS employment size-band dataset for the Annual Business Survey had published corrections for its 2023 results, including a processing error and later correction, so always use the latest corrected release when building 2026 baselines. ONS Annual Business Survey employment size-band dataset

2) Use size bands to shape your go-to-market

• Micro and non-employers: simpler offers, self-serve onboarding, lighter compliance, pricing that fits low admin time.
• Small (10 to 49): practical ROI narratives, team workflows, and basic IT or finance integration often start to matter.
• Medium (50 to 249): formal procurement and security checks become common, plus bigger rollouts.
• Large (250+): fewer targets, higher stakes, longer cycles, but large shares of employment and turnover.

3) A sensible 2026 scenario to watch

Estimate based on the long-run trend: if non-employing businesses continue to account for most net growth (as they did from 2010 to 2025), then the “typical” UK business in 2026 is likely to remain very small. That favours tools and services designed for owner-managers, and it also raises the bar on making complexity optional.

Common mistakes when quoting UK SME size stats

• Mixing “small businesses (0 to 49)” with “small employers (10 to 49)” in the same chart or sentence.
• Forgetting that turnover in this series excludes financial and insurance activities (so totals will not match some national accounts style totals).
• Assuming “no employees” means “no people”. The employment totals include owner-managers.
• Comparing start-of-year business snapshots with end-of-year register counts without noting the dates.

Conclusion

The UK’s business population in 2025 was dominated by very small firms, with small businesses (0 to 49 employees) making up 99.18% of all private sector businesses. Medium and large businesses were a tiny share by count, but large businesses accounted for a major share of employment and turnover. For 2026 planning, the biggest win is simply choosing the right “universe” for your work, business population for all businesses, Companies House for incorporated entities, and ONS survey outputs for detailed economic measures.