churnratio

Churn ratio, often referred to as churn rate, is a metric that expresses the share of customers who discontinue a service over a defined period. It is used to assess retention performance and potential revenue stability in subscription-based businesses, such as software as a service, telecommunications, and streaming services.

In its simplest form, churn ratio equals the number of customers lost during the period divided by the number of customers at the start of the period. Some analysts instead use the average number of customers during the period to reduce the impact of seasonal fluctuations. There are related concepts such as gross churn, which counts all lost customers, and net churn, which accounts for any customer gains such as new signups or expansions within the same period.

Churn ratio can be calculated for different timeframes—monthly, quarterly, or annually—and can be measured on a customer basis or a revenue basis. A customer-based churn ratio treats each lost customer equally, while a revenue-based churn ratio (revenue churn) expresses the value lost from churn as a share of total revenue, which is especially relevant when customers vary in plan size or usage.

Limitations include sensitivity to the base used and to count definitions (active vs dormant accounts, voluntary vs involuntary churn). Seasonality and cohort effects can distort single-period results, so many organizations analyze churn over multiple periods and by cohort.

Related metrics include retention rate, revenue churn, and lifetime value. Together, these metrics help diagnose product-market fit and forecast future revenue.