Capacity Testing
Capacity testing is a type of performance testing that determines the maximum workload a system can support while still meeting performance objectives.
“Testing to evaluate the capacity of a system.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Capacity Testing?
Capacity testing gradually increases workload to identify the point where performance no longer satisfies defined requirements. The results help determine system limits and scaling needs.
Goal: Identify maximum sustainable workload before unacceptable degradation occurs.
Measurement: Response times, throughput, and resource usage are monitored throughout the test.
Business value: Results support infrastructure planning and performance optimization.
Real World Example
A regulated product team is preparing a release where Capacity testing appears in reviews, test design conversations, or defect triage rather than as an isolated glossary word.
The risk is that the team treats Capacity testing as interchangeable with nearby ISTQB terms. That makes test scope blurry and can lead to weak evidence for the release decision.
The tester anchors the discussion in the official definition, asks where the concept appears in the product, and designs examples that show the difference between Capacity testing and similar ideas.
The page becomes useful in practice because Capacity testing is connected to a specific testing decision, not memorized as a detached definition.
Practice Questions
Question 1
Which outcome BEST represents capacity testing?
Question 2
Which mistake skews capacity results MOST?
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