Customer churn rate

Customer churn rate is the share of a defined starting customer population classified as having left under a stated rule. CFI describes churn in terms of customers stopping purchases from a business.[1] In a non-subscription store, that departure is not directly observable, so specify the inactivity rule and observation period used to classify a customer as lost.

Use lost customers from the original group as the numerator and that same starting group as the denominator. Newly acquired customers belong in neither. Churn and retention are complements only when they use the same population, period and exhaustive status rules. A customer who has not reordered a durable product may not actually have left; make the rule appropriate to the normal purchase cycle.