Free tools
SLA and uptime calculator
Turn an uptime percentage into the downtime it allows, or a downtime into the uptime it leaves.
Allowed downtime
Uptime from downtime
Uptime
Common SLA targets
| Uptime | Per day | Per week | Per month | Per quarter | Per year |
|---|---|---|---|---|---|
| 90% | 2h 24m | 16h 48m | 3d 1h 3m | 9d 3h 9m | 36d 12h 36m |
| 95% | 1h 12m | 8h 24m | 1d 12h 31m | 4d 13h 34m | 18d 6h 18m |
| 99% | 14m 24s | 1h 40m 48s | 7h 18m 18s | 21h 54m 54s | 3d 15h 39m |
| 99.5% | 7m 12s | 50m 24s | 3h 39m 9s | 10h 57m 27s | 1d 19h 49m |
| 99.9% | 1m 26s | 10m 5s | 43m 50s | 2h 11m 29s | 8h 45m 58s |
| 99.95% | 43.2s | 5m 2s | 21m 55s | 1h 5m 45s | 4h 22m 59s |
| 99.99% | 8.6s | 1m | 4m 23s | 13m 9s | 52m 36s |
| 99.999% | 0.9s | 6s | 26.3s | 1m 19s | 5m 16s |
How the calculator counts
Allowed downtime is the period length times the share of time the target leaves for outages: 99.9% allows 0.1% of each period. A year is 365.25 days, a month is a twelfth of that (30.44 days) and a quarter a fourth.
To know whether you meet an SLA, you need your real uptime. UptimeVanguard measures it around the clock (every 5 minutes on the Free plan, up to every 30 seconds on a paid plan) and keeps uptime reports per site.
Get alerted before your visitors notice
Measure your real uptime, with uptime reports and alerts when a site goes down.
Free plan: 3 sites checked every 5 minutes, with every check type and every alert channel. No card needed. Paid plans check every 60 seconds, and every 30 seconds for up to 10 HTTP or ping checks per team.