How to use this calculator
- Enter customers lost during period, customers at start of period.
- Choose a display currency, then select Calculate. Results also update after a brief pause while you edit.
- Read the result with the assumptions below. Export details or save a second scenario to compare your choices.
Formula and method
Customer churn rate = Customers lost during period ÷ Customers at start of period × 100%.
Assumptions and limitations
The lost count cannot exceed the opening cohort; define cancellation timing consistently.
Worked example
With customers lost during period = 20, customers at start of period = 500, customer churn rate is approximately 4%.
What the result means
Use losses from the opening cohort rather than dividing by an ending count inflated by new customers.
Common questions
How should I interpret customer churn rate?
Use losses from the opening cohort rather than dividing by an ending count inflated by new customers.
What should I check before using this result?
The lost count cannot exceed the opening cohort; define cancellation timing consistently.
Methodology and transparency
Calculation specification reviewed on 2026-10-14. Mathematical implementation is tested against independent reference fixtures. This does not imply review by a licensed financial professional. Read the testing and precision policy.