99% uptime: how much downtime?
An uptime of 99% (two nines) allows 7h 18m of downtime a month and 3d 15h 36m a year.
| Period | Allowed downtime |
|---|---|
| Per day | 14m 24s |
| Per week | 1h 40m 48s |
| Per month | 7h 18m |
| Per quarter | 21h 54m |
| Per year | 3d 15h 36m |
What 99% means in practice
Over seven hours of downtime a month still meets it, so one long outage can fit inside the target. Fine for internal tools and side projects, too loose for something customers pay to use.
A year is counted as 365 days and a month as a twelfth of that. Need another percentage, or the uptime from minutes of downtime? Use the uptime calculator.