Before you start
What you need
Starting customers, lost customers, new customers, and a period label.
Finance & Business Finance
Churn Calculator
Measure opening-cohort customer churn, retention, ending customers, and net customer change.
- 01Private browser calculation
- 02Assumptions stay visible
- 03CSV and print ready
Transparent method
How this calculation works
Customers lost are divided by starting customers. New customers affect ending count but do not reduce opening-cohort churn.
Useful output
What you receive
Customer churn, retention, ending customers, net change, assumptions, and CSV.
Decision guardrail
What this does not decide
Customer churn differs from revenue churn and does not show downgrades, reactivations, or cohort variation.
Practical uses
Where this tool helps
- Build a monthly retention snapshot.
- Explain growth despite churn.
- Check opening-cohort retention.
Data boundary
Financial inputs remain local
Calculations and report generation run in your browser. Nirmion does not upload, retain, or recover the values entered here. The public catalogue request contains only the tool slug.