Customer Churn Rate
Customer churn rate is the percentage of a starting customer population that is lost or becomes inactive under a defined rule during a period.
What is Customer Churn Rate?
For subscriptions, churn commonly follows customers who end their active relationship. For a conventional store, churn is usually inferred from inactivity because there is no cancellation event. The inactivity threshold needs to reflect the expected purchase cycle.
Customer churn counts people or accounts. Revenue churn measures the value lost and can behave differently when large and small customers leave. Name the count-based measure clearly.
Customer churn rate (%) = Customers lost from the starting population ÷ Starting customers × 100
Keep new acquisitions outside the starting denominator. State how pauses, reactivations and multiple subscriptions per customer are treated.
A monthly refill subscription loses 24 customers
A cosmetics subscription starts with 400 active customers. During the month, 24 from that starting group cancel and remain inactive at month-end. Under this end-state rule, customer churn is 6%. Fifty new signups can increase the total base while the same 6% churn still occurred.
How to interpret it
Churn describes attrition under the measurement rule. It can highlight a weak relationship or a mismatch between product expectations and experience, but the number alone does not identify why a customer left.
For non-subscription purchases, “no order in 180 days” is a classification threshold rather than proof that the person will never buy again. Durable products and replenishment products need different interpretations. Report inferred inactivity honestly.
Retention and churn sum to 100% only when they partition the same starting group into mutually exclusive retained and lost states over the same window. Definitions that include reactivation events or cumulative purchases can break that relationship.
Monthly rates should not simply be added to obtain annual churn. Under a constant 6% monthly churn assumption with no reactivation, annual retention would be 0.94 raised to the twelfth power. Real cohorts may also change their churn pattern as they age.
Common mistakes
Using ending customers as the denominator
The rate describes losses from the starting population. New customers arriving during the month should not dilute that loss rate.
Treating every inactive retail buyer as permanently lost
An observation rule helps reporting, but a long product replacement cycle can explain inactivity. Keep the threshold visible.