Task Completion Rate
Definition
The task success rate measures the proportion of attempts that successfully complete a defined task.
The task success rate is the proportion of attempts in which users successfully complete a clearly defined task according to specified criteria.
Simply explained
You count how many people complete a task by the same rules and relate this number to all attempts.
Why it matters in practice
The term helps to make digital offerings understandable, accessible, and aligned with users' needs.
Example from business
A test measures how many participants can find and download an invoice without help.
Limits and pitfalls
- Unclear success criteria, artificial tasks, and lack of segmentation obscure real problems; success says little about effort or satisfaction.
Origin & history
Task Success is an established usability metric in user-centered evaluation and ISO-oriented usability measurement.
Use in mid-sized companies
- Possible application: A test measures how many participants can find and download an invoice without help.
Frequently asked questions
What does task success rate mean?
The task success rate is the proportion of attempts in which users successfully complete a clearly defined task according to specified criteria. What should you watch out for? Unclear success criteria, artificial tasks, and lack of segmentation obscure real problems; success says little about effort or satisfaction.
Sources
- ISO 9241-11 overview · ISO 9241-11 overview
Source checked on 10.10.2026. Editorial application examples are hypothetical; no evidence of real customer results.
Editorially reviewed on: