CPI stands for Cost Per Install. And in mobile applications, CPI campaigns entail publishers placing digital ads across a range of media in an effort to drive installation of the advertised mobile app, and companies are charged when the application is installed. The Cost Per Install is determined by dividing the ad spend by a specific period of time by the number of new installs from that same period.
For example, if you spent $100 on ads for your app and acquired 82 new installs, your cost per install would be $100/82 = $1.22. However, there isn’t a standard CPI available for all apps, since there are many factors that determine the cost for every download. Factors that can influence CPI include the country, state, city (overall location) of the mobile user, the platform (i.e. the cost for each install is different from iOS app to Android apps), the mobile user acquisition channel (rates vary by social media platforms such as Facebook and Twitter), mobile app category, and even seasonal factors (given factors like substantial budgets that generally accompany holiday season mobile app acquisition and conversion campaigns).