CPI stands for Cost Per Install.
Definition of CPI (Cost Per Install)
CPI is a specialized billing model and performance metric used exclusively in mobile marketing:
- Billing Model – An advertising payment system where the advertiser pays a predetermined rate (or bids in an auction) for every successful installation (download and launch) of a mobile app that occurs as a result of an ad click.
- Performance Metric (KPI) – A metric that measures the average cost of acquiring one new app user through advertising campaigns.
The CPI model is fundamental to User Acquisition (UA) strategies for mobile apps, as the cost is directly tied to the primary business goal of expanding the user base.
CPI Formula:
CPI is calculated by dividing the total campaign cost by the number of app installations generated:
CPI = Total Campaign Cost Number of App Installations
Example: If 3,000 PLN was spent on a mobile app campaign and 1,000 installations were achieved, the CPI is 3 PLN.
CPI = 3,000 PLN 1,000 = 3 PLN
CPI vs. Other Metrics
CPI is closely related to other indicators as it represents the initial stage of the app conversion funnel:
- CPI vs. CPA: CPA (Cost Per Action) is a broader model that may include post-install actions (e.g., registration, subscription, or first in-app purchase). CPI focuses strictly on the cost of the download/install itself.
- Impact on LTV: While CPI measures acquisition cost, it must be compared against the LTV (Lifetime Value) of a user. If LTV is higher than CPI, the campaign is profitable.
- Factors Influencing CPI: Costs vary significantly based on the platform (iOS often has a higher CPI than Android), geographical location, and app category (e.g., games often face higher competition and thus higher CPIs).
