Uptime

Uptime is the share of time a service is available and working correctly, typically stated as a percentage such as 99.9% over a month or year. It’s the inverse of downtime, and small differences at the top of the scale matter a lot — each additional “nine” sharply reduces the allowed downtime.

How uptime is measured depends on what counts as “available,” so the check type and location matter. Continuous monitoring — including heartbeat monitoring for background jobs — is how teams observe it, and uptime targets are the basis of most SLAs.

Convert an uptime percentage into allowed downtime with the SLA uptime calculator.