System Reliability Calculator

Calculate MTTR, MTTF, MTBF, and availability from incident data or set targets to see allowed downtime budgets.

Allowed Downtime Budget

PeriodTwo 9s (99%)Three 9s (99.9%)Four 9s (99.99%)Five 9s (99.999%)
Per Year3d 15h 36m8h 45m 36s52m 33.6s5m 15.4s
Per Month7h 18m43m 48s4m 22.8s26.3s
Per Week1h 40m 48s10m 4.8s1m 0.5s6.0s
Per Day14m 24s1m 26.4s8.6s0.9s

Your Target Downtime

Understanding MTTR, MTTF, MTBF

MTTR (Mean Time to Repair) - Average duration to restore service after a failure. Lower is better. Tracks your team's incident response speed.

MTTF (Mean Time to Failure) - Average uptime between failures. Higher is better. Reflects system stability and preventive maintenance quality.

MTBF (Mean Time Between Failures) - Full cycle time: MTTF + MTTR. Represents the average interval from one failure onset to the next.

Availability = MTTF / (MTTF + MTTR) = MTTF / MTBF

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