Daily Active Users (DAU) is a mobile app metric that shows how many users visit an app in a 24-hour time period.
DAU shows developers how many users actively engage with their apps. Tracking this metric is important for app developers who expect users to use their apps every day (e.g. in mobile gaming). DAU is also used to calculate other important metrics, such as retention rates and lifetime values.
To calculate daily active users, there is no need to use a formula. Most app analytics tools can calculate this metric to determine how many unique users log into the app in a single day.