How do you forecast DAU for a mobile game?
DAU on any day is the sum of every past install cohort multiplied by the share of that cohort still active at its age. Fit a retention curve to your D1 and D30, apply it to your daily install plan, and add the cohorts up day by day.
Why does DAU keep growing even with flat installs?
Each day adds a new cohort while older cohorts decay slowly along the long tail of the retention curve. DAU rises until the users lost from old cohorts balance the users added by new ones — which can take many months for games with flat long-term retention.
What retention curve does this use?
A power law, R(t) = D1 × t^(−b), fitted exactly through your D1 and D30 values. Power laws describe mobile retention decay well in the first months; beyond your observed data they are an assumption, so treat long-horizon numbers as scenarios.
How much does a retention improvement change DAU?
More than the headline suggests, because every future cohort benefits and the gains stack across cohorts. Use the “improved D30” input to compare two curves directly.
Can I use this for non-game apps?
Yes. The mechanics are the same for any product measured by daily actives; just use your own D1 and D30 definitions consistently.