Formula
Users completing all onboarding steps / Users who started onboarding x 100
How to measure
Instrument each onboarding step as an event, then divide completions of the final step by starts of the first step.
Why track it
A low completion rate pinpoints exactly which step is losing users, turning a vague activation problem into a specific, fixable one.
Example
Of 500 users who start a 4-step onboarding flow, 210 finish all steps, an onboarding completion rate of 42%.