Chapter 5 – Test Management
Mean Time Between Failures (MTBF) – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
The arithmetic mean of the time between successive failures of a system.
In simple words
On average, how long the system runs between failures.
Exam tip
MTBF is a reliability metric, not an availability metric on its own.
Related terms
Practice this term in the ISTQB Mock Test
40 CTFL v4.0 questions, 60-minute timer, instant scoring and chapter-wise breakdown.
Practice in Mock Test