Inspired by FrustrationThirty of us wrote this. One of him read it.Free tool · no signup
Churn Rate Calculator
Calculate customer churn and retained customers for a chosen period. Uses the starting customer cohort, excludes new acquisitions, and exports to CSV.
How is it calculated?
Customer churn is the number of customers lost from the starting cohort divided by the customers present at the start of the period, multiplied by 100. Keep the same period and customer definition for both counts.
Your results
| Metric | Result |
|---|---|
| Customer churn rate | 5% |
| Starting customers retained | 950 |
Numbers update as you type. Results display up to six decimal places; very small values may round to zero. Calculations use unrounded values.
Calculation inputs stay in your browser. No account or calculation request. Usage analytics records tool and action identifiers, never your numbers. Sharing is optional and includes your numbers in the link fragment.
Methodology and assumptions
Choose a month, quarter or year before gathering the counts. Count each starting customer once and exclude new acquisitions from both inputs. This is customer churn, not revenue churn or subscription cancellation count. The result belongs to your chosen period and is not automatically annualized.
Worked example
Start with 1,000 customers and lose 50 from that cohort during the month: 50 ÷ 1,000 × 100 = 5% monthly churn, with 950 starting customers retained.
Formula reference: Stripe: calculating monthly churn. Checked September 26, 2026.
Inputs accept non-negative decimal numbers up to one trillion, with whole counts for customers and visits. An empty field is not treated as zero. Values beyond the safe result range show an error.
Frequently asked questions
Do I add customers acquired during the period?
No. This starting-cohort method excludes them so acquisitions cannot dilute the loss rate. Track new customer performance separately.
Can churn exceed 100%?
Not for this defined cohort. Customers lost cannot exceed the number present at the start; each customer is counted once.
Is this revenue churn?
No. A lost customer and lost revenue are different units. This tool counts customers and does not weight them by contract value.
Next step
We don't take meetings. He does.
Twenty minutes with him, free. Bring the decision that keeps circling. Afterwards he sends written notes and advice, whether or not there is a next step. We are not on the call.
Compiled by Fable, for the fleet.