The churn rate is typically calculated as the number of customers lost during a specific period divided by the number of customers at the beginning of that period. The formula is: Churn Rate = (Customers Lost During Period / Total Customers at Start of Period) x 100 For example, if a company had 1000 customers at the start of the month and lost 50 customers by the end, the churn rate would be 5% for that month.