What is a churn rate?
Short answer: Churn rate measures loss from an opening population during a period. Customer churn counts lost customers, logo churn counts lost organizations and revenue churn measures recurring revenue removed through cancellation or contraction. These measures answer different questions.
Gross churn records losses without giving credit for expansion or new customers. Net revenue retention includes expansion within the opening cohort and is therefore not a churn rate. A customer may be considered lost at cancellation, non-renewal, failed payment or the end of a grace period, so the event rule matters. Voluntary churn can reflect product, service or competitive issues. Involuntary churn can arise from payment failure or closure. Seasonal, project-based and non-contractual models may need a lapse or repeat-purchase measure instead of subscription churn.
How it works
Fix the opening population and exclude customers added during the period from the denominator. Define the loss event, treatment of pauses, downgrades, reactivations, mergers and related accounts. Reconcile opening customers plus additions less losses to closing customers. For revenue churn, use recurring revenue from the same opening cohort and keep currency treatment consistent. Analyze by acquisition cohort, product, tenure and reason rather than relying on a company average. Compare monthly and annual views using observed data. If annualizing, use compounding rather than multiplying a monthly percentage when that distinction is material.
Customer churn rate = customers lost during the period / customers at the start of the period
Example
A company starts the month with 1,000 active customers. Twenty cancel and five fail payment beyond the defined grace period, so 25 customers churn and monthly customer churn is 25 / 1,000 = 2.5%. Forty new customers join, making closing customers 1,015, but additions do not reduce gross churn. If the same 2.5% rate persisted independently each month, twelve-month retention would be (1 - 2.5%)^12 = about 73.8%, implying compounded annual churn of about 26.2%, not 30%.
Why it matters
Churn analysis should identify which customer or revenue losses threaten the operating plan and which product, service or commercial action can address them. Management and the board use cohort and reason data rather than a blended percentage alone. Buyers and investors test retention by contract, segment and customer concentration before underwriting recurring revenue. Lenders consider the downside effect on cash, especially when debt service depends on a stable recurring base.
A short period may be distorted by seasonality, renewal dates or a small denominator. Changing the loss rule can move churn without changing economics. Customer churn can appear low while high-value accounts contract, and revenue churn can hide loss of many small customers. Acquisitions and currency movements need separate treatment. Churn is company-defined and not governed by accounting standards, so external comparison requires aligned definitions and public disclosure may require method and change explanations.