Daily Active Users (DAU)
The number of unique users who engage with your product on a given day.
Definition
DAU counts the unique users who perform a meaningful action in your product within a 24-hour period. "Meaningful action" must be clearly defined - it should indicate actual engagement, not just opening the app. DAU is most relevant for products with daily use cases (messaging, social media, productivity tools). For products used weekly or monthly, WAU or MAU are more appropriate.
The DAU/MAU ratio (called "stickiness") is a key engagement metric. A DAU/MAU of 50% means the average user engages every other day. Facebook and WhatsApp achieve 60%+.
Why it matters for founders
DAU is a real-time pulse check on product health. A declining DAU trend signals engagement problems before they show up in revenue. For consumer and prosumer products, DAU growth is the metric investors watch most closely.
Example
When Instagram launched Stories in 2016, their DAU jumped from 300M to 400M within two months. Stories gave users a reason to open the app multiple times per day, driving the DAU/MAU ratio from 45% to over 55%.
How Foundra helps
Foundra's Validation Hypotheses card helps you define what "active" means for your product and set DAU targets tied to product-market fit evidence.
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Related terms
Monthly Active Users (MAU)
The number of unique users who engage with your product within a 30-day period.
Engagement Rate
A measure of how actively users interact with your product or content.
Activation Rate
The percentage of new users who complete a key action that predicts long-term retention.
North Star Metric
The single metric that best captures the core value your product delivers to customers.