one-line definition
DAU (Daily Active Users) counts the number of unique users who engage with your product on a given day.
formula: DAU = Unique users who performed at least one meaningful action in a 24-hour period
tl;dr
Define "active" carefully — a login alone shouldn't count. Track users who performed a core action (created something, completed a task, viewed a key page). Vanity DAU numbers hide engagement problems.
Simple definition
DAU counts how many unique users meaningfully engage with your product each day. It is the pulse check for products designed around daily habits. For solo founders, DAU reveals whether your product is becoming part of users' routines or just something they tried once. The critical nuance is in how you define "active" — counting logins or page views inflates the metric and hides real engagement problems. A strong DAU definition ties to the core value action that makes your product worth opening every day.
How to calculate it
DAU = Unique users who performed at least one meaningful action in a 24-hour period. First, define your qualifying action. For a task manager, it might be "created or completed a task." For a writing app, "wrote or edited a document." Then count distinct users who performed that action each day. If on Monday 142 unique users completed at least one task in your app, your DAU is 142. Track DAU as a daily time series and look at the 7-day and 28-day moving averages to smooth out weekday/weekend fluctuations. Most product analytics tools (Mixpanel, Amplitude, PostHog) calculate this automatically once you define the qualifying event.
Example
You run a daily journaling app. You initially define DAU as "users who opened the app," which gives you 340 DAU. Sounds great for an indie product. But then you redefine it as "users who wrote at least one journal entry," and DAU drops to 95. That means 245 people open the app daily without actually journaling — a massive engagement gap. You investigate and find the blank page is intimidating. You add a daily writing prompt that appears on open, and over 4 weeks your core-action DAU climbs from 95 to 185. The vanity DAU barely changed (350 vs 340), but real engagement nearly doubled. This is why the definition of "active" is the entire ballgame.
Related reading
Related terms
- MAU
- DAU/MAU Ratio
- Stickiness
FAQ
What counts as 'active' when calculating DAU?+
Define active as performing a core action — creating content, completing a task, or using a key feature. A bare login or passive page view inflates the number without reflecting real engagement.
Is DAU the right metric for my product?+
DAU matters for products designed for daily use (task managers, communication tools, habit trackers). If your product is used weekly or monthly (invoicing, analytics dashboards), WAU or MAU is a better fit.