Detailed view
How this calculator works
The answer does not change between Quick and Detailed. This is the professional finance underneath it — the formula, assumptions and mechanics you can inspect when you want the extra detail.
Retention curve
Retention curve = retained N / cohort size, for N = 1, 2, 3. The per-month survival of a same-period cohort — the headline metric for product-market fit.
Curve shape
A steep drop in month 1 followed by a flat line is normal — the rest arrives once a user has activated. A cliff after month 1 is an activation or churn issue at the time-of-purchase stage.
