◔ SLA & uptime calculator
Allowed downtime is the period multiplied by (100 - SLA) / 100. A 99.9% SLA allows 43 minutes 49 seconds a month and 8 hours 45 minutes 56 seconds a year; 99.99% allows 4 minutes 22 seconds a month. Enter any percentage to see the budget per day, week, month, quarter and year.
Enter an uptime percentage to see how much downtime it allows. Or enter minutes of downtime to see what uptime a month like that gives you.
The nines
Each extra nine cuts the budget tenfold: 99.9% is about 43 minutes a month, 99.99% about 4 minutes, 99.999% about 26 seconds.
Measure it honestly
Your SLA figure is only as good as the monitoring behind it. With 5-minute checks, a 4-minute outage may never show up at all.
Dependencies multiply
Two 99.9% services in series give about 99.8%. Your SLA can't beat the product of everything on the request path.
Measure your real uptime against your SLA
Vigil checks every minute from several locations, confirms failures before alerting, and turns the history into monthly SLA reports and public status pages with 90-day uptime bars.