Track retention across periods for a cohort and find where users are lost.
Retention is always measured against the original cohort size rather than the previous period, so the figures fall monotonically. What matters is whether the curve flattens, because a curve that flattens has found a group of users for whom the product works. The first period usually accounts for the largest loss, which makes onboarding the highest-leverage place to intervene rather than later-stage engagement.
Cohort Retention
Retention at period n = users still active ÷ original cohort size
Retention at period n = users still active ÷ original cohort size Retention is always measured against the original cohort size rather than the previous period, so the figures fall monotonically. What matters is whether the curve flattens, because a curve that flattens has found a group of users for whom the product works.
The first period usually accounts for the largest loss, which makes onboarding the highest-leverage place to intervene rather than later-stage engagement.
This calculator takes 4 inputs: Cohort size at signup, Still active after period 1, Still active after period 2, Still active after period 3. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.