Engineering Tool · SRE
Translate availability targets into allowed downtime budgets, or calculate the availability impact of an outage event.
Runs locally in your browser
What do the “nines” mean?
Availability targets become increasingly expensive as the tolerated outage window shrinks. Use the calculator for the exact budget over the measurement period you care about rather than relying on memorized examples.
Calculation model
Allowed downtime is derived from the unavailable fraction of the selected period: (1 - SLA/100) × period. The inverse view helps translate a real incident duration back into availability.