Definition
Time-on-Task measures efficiency by tracking how long it takes users to complete a defined action or workflow. Lower times generally indicate better usability, but context matters — a meditation app should have high time-on-task, while a checkout flow should be fast. This metric is most useful when compared before and after UX changes, where reductions indicate improved efficiency and increases may signal added confusion.
How to measure
Calculate the time delta between `task_start` and `task_complete` events. Report median (typical experience) rather than mean (skewed by outliers). Filter out abandoned sessions. Segment by user experience level (new vs. returning) and device type. Compare against previous versions of the same flow.
Industry benchmarks
Checkout flows: under 3 minutes. Form completion: 1–2 minutes for simple forms, 5–10 for complex. Onboarding wizards: under 5 minutes for best-in-class. A 20%+ reduction in time-on-task from a UX change is considered a significant improvement.