Install counts are easy to report and easy to celebrate. But an install is a cost, not an outcome. The value of a campaign shows up in what users do afterwards — and day-7 retention is one of the earliest reliable signals.
What D7 retention tells you
Day-7 retention is the share of users from a cohort who open your app seven days after installing. It filters out curiosity installs and accidental downloads, and it correlates well with longer-term engagement and revenue in most categories.
Comparing sources fairly
Always compare paid sources with your organic users as a baseline. If organic D7 is healthy and a paid source is far below it, that source is probably sending users who don't match your audience — or worse, traffic that isn't genuine.
- Compare cohorts of similar size and date range
- Look at retention by geo, since benchmarks vary widely between markets
- Check that onboarding changes aren't skewing results between periods
From retention to value
Once you have retention and revenue by cohort, you can calculate an effective cost per retained user and estimate ROAS. That's the number to optimise toward. A slightly higher CPI that brings users who stay is almost always the better deal.