The cost of one hour of downtime

Nobody can give you one universal number, but you can estimate your own in ten minutes.

Start with direct revenue

Take your average revenue per hour for the busiest realistic period and multiply by the share of the site that is affected. A shop that earns 500 per hour and loses checkout completely loses roughly 500 per hour.

Add the costs people forget

• Staff time. Engineers, support and managers pulled into the incident.
• Recovery work. Re-sending failed orders, fixing data, manual refunds.
• SLA credits. Money you owe customers directly.
• Ads you keep paying for. Campaigns continue to send traffic to a broken site.

And the costs that are harder to count

Lost trust, support tickets that arrive days later and search engines that see errors. These rarely appear on a spreadsheet, but they are why repeated short outages hurt more than their minutes suggest.

Turn it into a target

Once you have an hourly figure, multiply it by the allowed downtime for each uptime level. If 99.9% allows about 8 hours 45 minutes a year and an hour costs 2,000, that target accepts roughly 17,500 of risk. Whether that is acceptable — or worth paying to reduce — is a business decision, not a technical one.