Formula
Users active on Day 7 / Total new signups x 100
How to measure
Track a signup cohort and measure the percentage who trigger an active-use event on day 7 after signup.
Why track it
D7 retention indicates whether a user has formed an early habit beyond a single first-session curiosity visit.
Example
A habit-tracking app finds 30% of new users are still active on day 7, its clearest early signal of long-term stickiness.