Chapter 5 – Managing the Test Activities
Mean Time To Repair (MTTR) – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
The arithmetic mean of the time needed to repair a failed component or system.
In simple words
The average time from a failure to the system being back up.
Exam tip
MTTR + MTBF give you availability: Availability = MTBF / (MTBF + MTTR).
Related terms
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