Cost Per Install (CPI)
CPI is the average amount spent in advertising to generate one app install. It's the most common efficiency metric in mobile user acquisition.
Definition
Cost per install (CPI) measures how much an advertiser pays, on average, for each app install delivered by their ad campaigns. It's the primary efficiency metric for top-of-funnel mobile UA, the cost to fill the acquisition funnel with new users.
CPI is calculated by dividing total ad spend by the number of installs attributed to that spend. It combines media cost efficiency (CPM) and creative-to-install conversion efficiency (IPM) into a single number. Reducing CPI requires improving one or both inputs: lowering the CPM paid for impressions or increasing the install rate per impression.
CPI benchmarks are highly category-dependent. Hyper-casual games often achieve $0.20–$1.00 CPI. Mid-core games typically see $2–$8. Apps in competitive verticals like fintech or B2B SaaS may see $10–$40+ CPI on paid social.
Why it matters
CPI determines how efficiently you can scale. If your CPI is below your LTV payback threshold, you can scale spend profitably. Above it, you're buying unprofitable users. CPI is also the most direct feedback signal for creative performance, when creative quality improves, CPI drops. When fatigue sets in, CPI rises. It's the single fastest way to measure whether your creative strategy is working.
Formula
CPI = Total Ad Spend ÷ Number of Installs
Example
In practice
A gaming studio spends $25,000 on a Meta campaign and records 12,500 installs, a $2.00 CPI. By rotating to a stronger creative, installs rise to 18,750 at the same spend, dropping CPI to $1.33, a 33% efficiency improvement.
Frequently asked questions
What is a good CPI for mobile apps?
Hyper-casual games: $0.20–$1.50. Mid-core/RPG games: $2–$8. Subscription apps: $4–$15. DTC e-commerce: $2–$10. Utility apps: $3–$20. These ranges shift significantly based on country, platform, and targeting.
What's the difference between CPI and CPA?
CPI measures cost per install (top of funnel). CPA (cost per action) measures cost per specific in-app event, a purchase, subscription start, or level completion. CPA is a more downstream metric measuring quality users, not just installed users.
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