Churn represents the percentage of subscribers to a service who discontinue their subscription in a given time period. Churn is expressed by the formula:
(number of subscriptions expired during the period) / (number of subscriptions paid at the beginning of the period) * 100.
In order for a company to expand its customer base, its growth rate (number of new customers) must exceed its churn rate (number of lost customers).
Churn allows you to identify lost subscribers in the same way that Trial Conversion allows you to identify gained subscribers: both charts are indispensable for making long-term product forecasts.