How much does IT downtime cost a small business?

For a 10-person business on average UK salaries, one hour of total downtime costs at least £170 in wages alone. Add lost billable time, cleanup and recovery work, and potential client trust damage, and the real cost is often two to three times higher. A half-day outage for a team of ten could easily cost £1,500 to £3,000.

What causes the most downtime for small businesses?

The most common causes of small business IT downtime are: broadband failure, an ageing server or NAS device, ransomware incidents, failed Windows updates, and human error. Four of the five are preventable with good IT planning.

How can a small business reduce the risk of IT downtime?

Key steps include: having a 4G/5G broadband failover so an internet outage does not stop work, moving email and files to Microsoft 365 so they do not depend on your office, maintaining tested backups, keeping a written recovery plan, and using a managed IT support provider with a clear response-time commitment.

A frustrated small business owner at a desk staring at a laptop showing a system error

Written by Phil on 16 January 2026.

The Real Cost of Downtime for a Small Business

"How much does downtime actually cost us?" is a question I hear almost every week, usually after a business has just lost half a morning to a dead internet connection or a frozen server. The honest answer: far more than the hourly salary cost most owners assume.

Downtime is quiet until it isn't. Then it swallows a whole day. Here is how I walk clients through the real numbers, and what to do so you stop paying them.

Start with the obvious: wages paid for no output

If you have ten staff on an average salary of £30,000, each person costs roughly £17 an hour once you add employer NI and pension. An hour of total downtime with everyone sat at their desks is already £170 in wages for nothing.

That is the easy number to calculate. It is rarely the biggest number.

Then add the revenue you didn't earn

If your team is the business (accountants, consultants, solicitors, agencies), then lost hours are lost billable time. A team of ten charging £80 an hour who lose half a day have lost £3,200 in potential revenue. You won't get most of that back by working late.

For a shop or a trade business that takes orders online, the cost is even sharper. If your card machine, booking system, or Shopify store goes down, you lose the sale completely. Customers go elsewhere and rarely come back.

Add the cleanup cost

After the outage, someone has to rebuild what was lost. Orders re-entered by hand. Emails chased up. Clients rung to apologise. Quotes redone. That hidden tail of admin often doubles the original impact of the outage; one lost hour becomes two hours of recovery.

If an engineer (mine or yours) has to come out and fix the root cause, that is another £250 to £800 depending on the problem.

Don't forget trust

This one is impossible to put a number on, but it matters. If a client rings you twice and gets an out-of-office because your email has been down for six hours, they start to wonder whether you are a safe pair of hands. For professional services in particular, repeated outages erode the confidence you spent years building.

What actually causes downtime in a small business

In my experience the main culprits are, in order: broadband failure, a single ageing server or NAS, a ransomware incident, a failed Windows update, and human error (usually someone unplugging the wrong cable). Four of those five are preventable with reasonable planning. The fifth is cheaper to recover from than most people think, if you've prepared.

How to bring the risk down

I don't sell a magic "zero downtime" product; no one can. What I do recommend for small businesses:

A second broadband line on a different network (4G/5G failover counts) so a cable cut doesn't stop you.
Move email, files, and line-of-business systems to Microsoft 365 or another cloud service so they don't depend on your office.
A proper backup that is tested, not just taken. An untested backup is a guess, not a plan.
A written recovery plan, even a one-pager, so the first 30 minutes of an outage aren't wasted working out who does what.
Managed IT support with a clear response-time commitment so you aren't ringing round for help when the clock is ticking.

Work out your own hourly cost

If you want a rough number for your own business, add:

Total hourly wage cost of everyone affected (salary divided by ~1,700 working hours, plus 13.8% NI).
Lost billable or sales revenue for that hour.
A 50% uplift for cleanup and follow-on admin.

For most Kent small businesses I work with, a full hour of downtime sits somewhere between £400 and £2,000. Two or three outages a year adds up to real money.

One final thing

Downtime is one of the few things in running a business where a small, boring monthly spend (resilient broadband, cloud services, tested backups, a responsive support provider) genuinely saves you from a big, painful one-off cost. The businesses I support that have invested in those basics don't call me in a panic. They call to ask unrelated questions, because things just keep working.

If you'd like a no-jargon review of what an hour of downtime would actually cost your business, and what's realistic to do about it, get in touch and I'll come and look at your setup.

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