What is user acquisition trying to achieve?
User acquisition (UA) is the process of reaching people who are a good fit for a product and helping them reach a meaningful first experience. Media channels, audience choices, creative work, budgeting and measurement all play a role.
The goal is not volume for its own sake. The promise in an ad should match the experience that follows installation.
CPI: What does an install cost?
Cost per install divides eligible advertising spend by attributed installs over a defined period. It is useful for comparing acquisition efficiency across campaigns.
A low CPI does not automatically mean high-quality users. Attribution windows, markets, platforms and objectives vary, so comparisons must use consistent definitions.
Retention: Do people come back?
Retention describes the share of a starting group that returns on later days or periods. D1, D7 and D30 are common views, but their meaning depends on how often the product is naturally used.
An occasional purchase app should not be judged exactly like a daily habit tracker. Focus on your own usage cycle and compare cohorts instead of hunting for one universal benchmark.
ROAS: What revenue follows the spend?
Return on ad spend is attributed revenue divided by advertising spend. If a campaign spends $10,000 and records $15,000 in attributed revenue, its ROAS is 1.5, or 150%.
That number is not equivalent to profit. Operating costs, margins, platform fees and attribution limitations matter. The time it takes revenue to materialize also changes the interpretation.
Put the metrics into one decision framework
Imagine two campaigns. One delivers lower-cost installs but weak engagement. The other looks expensive at first, yet those users return more often and generate more revenue. CPI alone could lead you to stop the better campaign.
Analyze cohorts by source, market, creative and acquisition date. Look at activation, retention and revenue together, and be transparent about any privacy-driven measurement gaps.
- Define the business goal before optimizing.
- Review CPI alongside activation and retention.
- Evaluate revenue over an appropriate time horizon.
Optimize for useful growth, not cheap installs
CPI explains acquisition cost, retention shows ongoing engagement, and ROAS connects spend with revenue. Their value comes from interpreting them together in the context of your product.