eCPI
Also: Effective Cost Per Install
eCPI (effective cost per install) is total ad spend divided by all installs in the period, including organic ones. It captures the organic lift that paid campaigns generate through chart position and word of mouth.
eCPI = Ad spend ÷ (Paid installs + Organic installs)
Paid campaigns lift an app's store ranking, and higher ranking produces organic installs the ad networks never see. eCPI credits that uplift to the spend, which is why it is lower than CPI and closer to what the business actually paid per new user.
The trap is the reverse: eCPI also absorbs organic installs that would have happened anyway. Use it as a planning number, and use incrementality testing to find the real multiplier.
Related terms
In Roasy
Roasy computes this across every ad network, Adjust, and RevenueCat on one screen — real revenue, cohort windows, and the same definition everywhere.