Churn is typically calculated in two broad categories: revenue churn, which measures the dollar value of contracts that are not extended, and consumer churn, which is commonly expressed as the percentage of companies up for renewal that does not extend their contract. There are some more detailed views within each of these types, ranging from the predictable (net vs. gross or churn within company size or market cohorts) to the complex [preventable churn (unhappy clients, inactive users) vs. systemic churn (customer went out of business or was acquired)].
