What an uptime promise really covers

What 99.9% means in hours, what a host can and cannot promise, and how to measure it yourself.

Hosting plans often promise an uptime percentage. The number sounds close to perfect, but it is easier to judge in hours.

The percentage in hours

99% allows about 3 days and 15 hours of downtime a year. 99.9% allows about 8 hours and 45 minutes. 99.99% allows about 52 minutes. The calculator on our home page converts any percentage.

What it usually covers

An uptime promise normally covers the server and the network. It does not cover a website broken by its own code, an expired domain, or a plugin update that fails.

Measure it yourself

The only uptime figure that tells you about your site is one measured from outside it, every few minutes, by something that is not your host. That is what a monitor does.