Churn Rate, also known as customer attrition rate or employee turnover rate, is a metric used to measure the rate at which customers or employees disengage, leave, or stop using a product or service over a specific period. It indicates the percentage of customers or employees who cease their relationship with a company during a given time frame.

Example
In the context of customer churn, a software-as-a-service (SaaS) company may calculate its churn rate by dividing the number of customers lost during a month by the total number of customers at the beginning of the month. If the company had 500 customers at the start of the month and lost 20 customers, the churn rate would be 20 divided by 500, resulting in a churn rate of 4%. This means that the company is experiencing a monthly customer churn of 4%. Similarly, in the context of employee churn, an organization may calculate the employee churn rate by dividing the number of employees who left the company during a specific period by the average number of employees during that period. A high churn rate, in either case, may indicate underlying issues that need to be addressed, such as product dissatisfaction, poor customer service, or workplace concerns, in order to improve customer or employee retention.