How much downtime is 99.5% uptime?

99.5% uptime is a common target for small business websites that are useful but not critical. It allows about three and a half hours of downtime a month.

What does 99.5% uptime mean in practice?

Half a nine is a step up from 99% that mostly comes from noticing problems sooner and fixing them the same day. A site at 99.5% can afford one real outage a month, as long as it is fixed within a few hours.

Who is 99.5% uptime right for?

• A brochure site for a local business
• A blog that earns indirectly
• A client site with no online sales

Who should aim higher?

Checkout pages, booking systems and anything where an hour of downtime costs the client money directly.

What does it take to reach 99.5% uptime?

Getting to 99.5% usually means external monitoring with alerts to your phone, a host with a good track record and a habit of checking after each deploy. It rarely needs redundant infrastructure.

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 - 99.5) / 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.