Chapter 5 – Managing the Test Activities
Failure Rate – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
The ratio of the number of failures of a given category to a given unit of measure, e.g. failures per unit of time.
In simple words
How often the software fails per hour, per transaction, per run.
Exam tip
Failure rate is the raw input for reliability metrics (MTBF, MTTF).
Related terms
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