One hour of IT downtime typically costs an SMB anywhere from a few hundred to several tens of thousands of euros, depending on how much of its business runs on digital systems. The calculation rests on four components: lost hourly revenue, unproductive payroll, remediation costs, and hidden costs such as reputation damage or contractual penalties. For a 30-person services company, the bill most often lands between 2,000 and 5,000 euros per hour of unavailability.
Why this cost is almost always underestimated
Ask a business owner what an outage costs and the spontaneous answer is usually limited to the invoice of the technician who came to fix it. That is the tip of the iceberg. An outage triggers a cascade: teams stop producing, orders stop coming in, customers grow impatient, and every hour spent firefighting is an hour stolen from ongoing projects. In 2026, with IT systems more interconnected than ever — CRM, ERP, IP telephony, e-invoicing — a single failure often paralyses several functions at once. And the longer the outage lasts, the less linear the damage becomes: the second hour generally costs more than the first, because backlogs pile up and workarounds multiply.
The simple formula to apply
The real cost of one hour of unavailability can be approximated by adding four components:
- Lost hourly revenue: (annual revenue ÷ annual working hours) × share of the business that depends on the affected system.
- Unproductive payroll: number of blocked employees × average fully loaded hourly cost × unproductivity rate during the outage.
- Remediation costs: emergency intervention, overtime, hardware replacement, re-entering lost data.
- Hidden costs: contractual penalties, lost customers, reputation damage, missed opportunities.
The first three items can be quantified in minutes with your accounting data. The fourth is harder to estimate, yet it is often the heaviest over time.
A worked example: a 30-person SMB
Take a fictional 30-person services company generating 4 million euros in annual revenue, or roughly 2,270 euros of revenue per working hour (based on 1,760 hours per year). Its ERP and email go down on a Tuesday morning.
- Lost hourly revenue: 60% of the business depends on the affected tools, or about 1,360 euros per hour.
- Unproductive payroll: 30 employees at a loaded cost of 32 euros per hour, 70% unproductive, or about 670 euros per hour.
- Remediation: an emergency intervention billed between 500 and 1,500 euros depending on timing and complexity.
Result: between 2,200 and 2,700 euros per hour, before even counting hidden costs. A four-hour outage exceeds 10,000 euros — the equivalent of several months of prevention budget.
Indicative ranges by company profile
As a rough guide, keeping in mind that every situation is unique:
- B2B services SMB (20 to 50 people): generally 1,000 to 5,000 euros per hour, driven mostly by unproductive payroll.
- E-commerce: lost hourly revenue is direct and immediate; during peak periods it can exceed 10,000 euros per hour on its own.
- Manufacturing and logistics: a production line or warehouse stoppage adds restart costs and chain-reaction delays that are hard to recover.
- Regulated activities (healthcare, finance, legal): penalties and continuity obligations significantly inflate the bill.
Hidden costs: reputation, churn, penalties
The invisible costs materialise after the outage. A customer whose order was lost starts comparing suppliers. A prospect who finds your website offline does not come back. Missed service-level commitments trigger penalties or credit notes. And internally, repeated outages erode the teams' trust in their tools, which durably degrades productivity. Insurance premiums can also rise after a major incident, and the management time spent handling the fallout is never invoiced anywhere. These effects are deferred and diffuse, which explains why they are rarely included in the calculation — wrongly so.
Why prevention almost always costs less
Against these figures, the cost of prevention suddenly looks reasonable. Serious monitoring that detects the incident before the users do, tested backups that guarantee a fast restore, even a modest disaster recovery plan: for an SMB, the whole package generally represents a few hundred euros per month, infrastructure included. In other words, less than the cost of a single multi-hour outage in our example. Prevention does not eliminate the risk, but it turns multi-hour outages into incidents lasting a few minutes. It also shortens the incidents that do happen, because teams that monitor their systems know exactly where to look when something breaks.
Invest or accept the risk? A simple decision tree
- Calculate your hourly cost with the formula above, system by system.
- Estimate your annual exposure: plausible hours of downtime per year × hourly cost.
- Price out prevention: monitoring, backups, redundancy, a support contract.
- Compare: if prevention costs less than the exposure — which is almost always the case for critical systems — invest.
- Consciously accept the residual risk on secondary systems, and document that choice so it can be reviewed every year.
This trade-off is never final: it should be revisited as your dependence on digital systems grows.
The hard part is not the formula but the honesty of the inventory: knowing precisely which systems carry your revenue and what happens when they stop. This is exactly the kind of exercise an outside perspective accelerates: a technical partner familiar with SMB infrastructures can quantify your real exposure and size the prevention effort accurately, without over-investing.