Churn rate is the percentage of clients your company loses every year. Let’s say you start with 100 clients on January 1st. Fro these 100, 10 stop buying from you. Your churn rate is going to be 10%.
The formula is Number of clients at the beginning of the year – Number of clients lost at the end of the year (who stopped purchasing from you) / Number of clients at the beginning of the year.