SLA Uptime Calculator
Convert an uptime percentage into allowed downtime over common reporting periods.
Use it when reviewing a vendor agreement, setting an internal target, or checking the effect of another decimal place.
%
Allowed Downtime
Per Day
1m 26s
Per Week
10m 5s
Per Month (30d)
43m 12s
Per Year
8h 45m 36s
Common SLA Levels
| SLA Level | Nickname | Downtime / Year | Downtime / Month |
|---|---|---|---|
| 99% | Two nines | 3d 15h 36m | 7h 18m |
| 99.5% | Two and a half nines | 1d 19h 48m | 3h 39m |
| 99.9% | Three nines | 8h 45m 36s | 43m 12s |
| 99.95% | Three and a half nines | 4h 22m 48s | 21m 36s |
| 99.99% | Four nines | 52m 33.6s | 4m 19s |
| 99.999% | Five nines | 5m 15.4s | 25.9s |
How the calculation works
A Service Level Agreement (SLA) defines the expected uptime for a service. For example, a "three nines" (99.9%) SLA means the service can be down for no more than 8 hours and 45 minutes per year. This calculator converts any SLA percentage into exact allowed downtime across different time periods.
Compare the target with observed history
ServiceAlert records provider status history and owned-monitor results. Use the calculator for the contractual allowance, then compare it with the measurement method defined in the agreement.