Daily Active Users (DAU)

Unique users who engage with your product in a single day.

Vanity Risk

Without retention context, DAU is a vanity metric. A viral spike that fades within two weeks signals temporary interest, not real growth. Always pair with retention curves.

DAU = Unique users with ≥1 qualifying action per day

What it measures

Count of unique users with at least one qualifying action in a 24-hour period. What counts as "active" is product-specific: it might be logging in, viewing content, or completing a core action like sending a message.

What to watch

Rising: Indicates growing engagement, but verify sustainability. A viral spike that fades within 7-14 days signals temporary interest, not real growth. Pair with retention metrics.
Falling: Could signal product issues, seasonality, or a shift in user behavior. Segment by cohort to identify whether it's new user acquisition or existing user engagement that's declining.

In practice

After launching push notifications, a productivity app saw DAU jump 40% in week one. But sessions per user dropped from 3.2 to 1.8. Users opened the app more but did less each time. The team shifted to weekly digest notifications, which recovered session depth while maintaining the DAU gain.