99.999% uptime: how much downtime?
An uptime of 99.999% (five nines) allows 26.28 s of downtime a month and 5m 15s a year.
| Period | Allowed downtime |
|---|---|
| Per day | 864 ms |
| Per week | 6.05 s |
| Per month | 26.28 s |
| Per quarter | 1m 19s |
| Per year | 5m 15s |
What 99.999% means in practice
About 26 seconds a month. It requires redundancy in every layer and is rarely a sensible promise for a single web application.
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.