Churn

Churn is the rate at which customers, users, or subscribers leave. It is the outflow in a stock-and-flow system: the customer base is the stock; acquisition is the inflow; churn is the outflow. Net growth is inflow minus outflow. When churn equals or exceeds acquisition, growth stops or reverses. The strategic implication is direct: you can grow by adding more customers or by losing fewer. At scale, reducing churn often has higher leverage than increasing acquisition because retained customers compound (renewals, expansion, referral) while acquired customers must first be retained. Churn rate and retention rate are two sides of the same coin; the discipline is measuring both and understanding what drives exit.

Churn is not a single number. Cohort churn (what share of a given signup cohort remains after 1, 6, 12 months) reveals whether retention is improving over time. Gross churn (customers lost in a period) and net churn (gross churn minus expansion revenue from remaining customers) matter for revenue. In subscription businesses, net revenue retention above 100% means expansion from the base outweighs churn; below 100%, the base is shrinking. The best companies obsess over churn by cohort and by segment. They know why people leave and act on it — product, support, pricing, or fit. The worst treat churn as inevitable and pour more into acquisition to compensate. That strategy is a treadmill: faster acquisition masks churn until the funnel gets expensive and growth stalls.

Voluntary churn (customer chooses to leave) and involuntary churn (payment failure, compliance, ban) have different causes and cures. Reducing voluntary churn improves product-market fit, value delivery, and switching costs. Reducing involuntary churn improves billing, dunning, and fraud handling. Both improve the same metric but require different interventions. Map churn by type and by segment. Then prioritise: where is churn highest, and what would move the needle?