How much downtime is 99.99% uptime?

99.99% uptime, four nines, allows only about four minutes of downtime a month. It is the level written into contracts for services that businesses cannot do without.

What does 99.99% uptime mean in practice?

At four nines there is no room for a manual response. A person noticing, logging in and fixing takes longer than the whole monthly allowance, so failures must be detected and routed around automatically.

Who is 99.99% uptime right for?

• Payment and checkout infrastructure
• APIs that other products depend on
• Platforms with contractual downtime penalties

Who should aim higher?

A typical small client site. The infrastructure to deliver four nines, multiple regions, redundant databases and automated failover, costs far more than the downtime it prevents.

What does it take to reach 99.99% uptime?

It needs redundancy at every layer, health checks that remove failing nodes within seconds, deploys that do not cause downtime and monitoring from several regions. A single host cannot deliver it.

How is the downtime calculated?

The allowed downtime is the length of the period multiplied by the share of it you may be down: period x (100 - 99.99) / 100. The table uses a month of one twelfth of a 365-day year. A contract that says "per month" may define a month differently, so check the wording. Use the uptime and SLA calculator for any other percentage, or to turn the downtime you had into an uptime figure.

How do I know what uptime I actually deliver?

You cannot promise an uptime you do not measure. Run external checks that confirm failures before alerting, keep the check history and report the real number each month. Our guide on setting up uptime monitoring for client websites shows how.

Where Datumboard fits

Datumboard shows the health of every client site next to deploys, renewals, search data and costs, so a failing site is at the top of one list. It is in early access, and you can join the list below.