What Is Cost Per Install (CPI)?
Cost per install (CPI) is a mobile advertising pricing model in which an advertiser pays only when a user downloads and installs their app. It is the standard performance metric for mobile user acquisition campaigns, giving marketers a direct measure of how much each new app user costs to acquire.
CPI sits alongside cost per click and cost per action as one of the core pricing models in performance marketing, but it is specific to mobile environments where the install event is the measurable conversion.
CPI Formula
The calculation is straightforward:
| Formula | Example |
|---|---|
| CPI = Total Ad Spend ÷ Number of Installs | $50,000 ÷ 10,000 installs = $5.00 CPI |
If a gaming studio spends $120,000 across a Meta Advantage+ campaign and records 24,000 installs, the CPI is $5.00. That figure becomes the baseline against which all subsequent campaigns are measured.
Industry Benchmarks
CPI varies significantly by platform, category, and geography. The figures below reflect general market ranges based on industry reporting from AppsFlyer and Sensor Tower.
| Category | iOS CPI (US) | Android CPI (US) |
|---|---|---|
| Casual Gaming | $1.50 – $3.00 | $0.50 – $1.50 |
| Midcore / Strategy Gaming | $3.00 – $8.00 | $1.50 – $4.00 |
| Finance / Fintech | $8.00 – $25.00 | $5.00 – $15.00 |
| E-commerce | $2.00 – $6.00 | $1.00 – $3.00 |
| Health & Fitness | $3.00 – $9.00 | $1.50 – $4.50 |
iOS installs consistently cost more than Android installs in the same market. Apple’s App Tracking Transparency (ATT) framework, introduced in 2021, reduced signal fidelity for advertisers and compressed targeting efficiency, pushing iOS CPI higher across most verticals.
CPI vs. eCPI
Effective CPI (eCPI) accounts for blended spend across multiple channels, including organic installs that a paid campaign indirectly influenced. If a campaign drives both paid and organic lift, eCPI provides a more realistic cost picture than raw CPI alone.
eCPI = Total Marketing Spend ÷ (Paid Installs + Attributed Organic Uplift)
Supercell, the Finnish mobile gaming company behind Clash of Clans, has publicly acknowledged that brand-level TV and social campaigns generate measurable organic install uplift. Measuring only paid CPI in those scenarios understates return on investment and overstates the cost of acquisition.
What Drives CPI Up or Down
Creative Quality
Ad creative is the single largest lever advertisers control. Playable ads and short-form video consistently outperform static banners in gaming categories. InMobi data suggests that playable ads can reduce CPI by 20 to 40 percent compared to standard display formats in the same campaign.
Audience Targeting
Broad targeting often produces lower CPI but attracts low-intent users who uninstall quickly. Narrow targeting using lookalike audiences built from high-lifetime value users typically raises CPI while improving downstream revenue metrics. The right balance depends on the app’s monetization model.
Platform and Placement
Meta (Facebook and Instagram), Google UAC, and Apple Search Ads dominate mobile user acquisition spending. Apple Search Ads captures users with demonstrated purchase intent at the moment of search, which typically results in higher CPI but stronger post-install engagement. Google UAC’s automated optimization across Search, YouTube, Display, and Play tends to find lower-CPI volume at scale, though quality varies by vertical.
Seasonality
Q4 auction pressure from retail advertisers inflates CPMs across all digital channels, which pushes CPI higher for app advertisers who are not the primary seasonal category. Gaming studios commonly front-load user acquisition spend in Q1 and Q2 to avoid elevated Q4 costs.
CPI as a Leading Indicator, Not a Final Metric
A low CPI is not inherently good. An app that acquires users at $0.80 but sees 80 percent of them churn within 48 hours generates negligible revenue. CPI is most useful when paired with post-install metrics such as Day 1, Day 7, and Day 30 retention rates and lifetime value.
The relevant question is whether CPI sits below the revenue a user generates over their lifetime. For a subscription fitness app with a $60 annual plan and a 30 percent conversion rate from free install to paid, the allowable CPI threshold is roughly $18 before accounting for operating costs. An app paying $22 CPI in that scenario is losing money on every install regardless of volume.
CPI in Programmatic and DSP Buying
When buying through a demand-side platform, advertisers rarely purchase on a guaranteed CPI basis. Instead, they bid on CPM (cost per thousand impressions) or CPC and calculate an effective CPI by dividing total spend by resulting installs. Programmatic platforms such as The Trade Desk and DV360 allow app advertisers to optimize toward install events using modeled conversions, though attribution accuracy has declined since ATT and Google’s Privacy Sandbox changes reduced device-level identifiers.
Performance Networks and CPI Guarantees
Networks such as ironSource (now part of Unity), Digital Turbine, and Moloco operate on performance-based CPI guarantees, charging only for verified installs rather than impressions or clicks. These networks carry higher base rates but reduce waste from impression spend that does not convert.
Tracking and Attribution
CPI measurement depends on a mobile measurement partner (MMP) to attribute installs to the correct ad source. AppsFlyer, Adjust, and Branch are the dominant MMP providers. MMPs assign each install a source attribution based on click or impression data within a defined attribution window, typically one to seven days for clicks and one day for view-through conversions.
Discrepancies between MMP-reported installs and network-reported installs are common. Networks count every download associated with a click; MMPs apply deduplication and last-touch attribution rules. Advertisers should treat MMP data as the authoritative source for billing reconciliation and return on ad spend calculations.
Frequently Asked Questions
What is a good CPI for a mobile app?
A good CPI depends on the app category, platform, and target market. Casual mobile games on Android can achieve competitive CPI below $1.50 in the US market. Finance and fintech apps on iOS routinely exceed $10.00, which is acceptable when lifetime value justifies it. The right threshold is one where CPI stays below the revenue each user generates over their lifetime with the app.
Why is iOS CPI higher than Android CPI?
iOS CPI runs higher than Android across most app categories because Apple’s App Tracking Transparency (ATT) framework, introduced in 2021, reduced the targeting data available to advertisers. Less signal means less precise audience targeting, which raises the cost of finding qualified users at scale.
What is eCPI and how is it different from CPI?
eCPI (effective cost per install) accounts for both paid installs and organic installs that a campaign indirectly influenced. Standard CPI measures only paid installs tied directly to ad spend. eCPI gives a more complete picture of total acquisition cost when brand campaigns drive organic download lift alongside paid results.
How do mobile measurement partners affect CPI reporting?
Mobile measurement partners (MMPs) such as AppsFlyer, Adjust, and Branch are the authoritative source for install attribution. They deduplicate installs and apply last-touch attribution rules, which typically produces lower install counts than what ad networks self-report. Advertisers use MMP data for billing reconciliation because it filters for verified, unique installs only.
What is the fastest way to lower CPI?
Creative quality is the single largest lever. Switching from static banner ads to playable ads or short-form video can reduce CPI by 20 to 40 percent within the same campaign, according to InMobi data. Audience targeting refinements and bid strategy adjustments also move CPI, but generally have smaller impact than a strong creative refresh.
Key Takeaways
- CPI = Total Ad Spend ÷ Number of Installs. It measures the direct cost of each new app user from paid campaigns.
- Benchmarks range from under $1.00 for Android casual games to over $20.00 for iOS fintech apps in the US market.
- iOS CPI runs higher than Android across most categories due to reduced targeting signal after ATT.
- CPI should always be evaluated against post-install retention and lifetime value to determine whether acquisition spend is profitable.
- MMP data, not network-reported data, is the standard for install attribution and billing verification.