Churn Rate Calculator
Measure how many customers you lose and how long the average one stays.
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Churn Rate Calculator by TheCalcTools
How the Churn Rate Calculator works
Enter customers at the start of the period and how many left during it.
Churn is lost ÷ starting customers; retention is the remainder.
Lifetime is the period divided by the churn rate; annualised churn compounds the rate over 12 months.
The formula
Worked example
Using the default values shown in the calculator:
| Customers at start | 1000 |
|---|---|
| Customers lost | 45 |
| Period length (months) | 1 |
- Churn = 45 ÷ 1,000 = 4.50%.
- Retention = 95.50%.
- Average lifetime ≈ 22.2 months; annualised churn ≈ 42.5%.
Result:
| Churn rate | 4.50% |
|---|---|
| Retention rate | 95.50% |
| Average customer lifetime (months) | 22.2 |
| Annualised churn | 42.5% |
Frequently asked questions
Should new customers be in the denominator?
No. Use only the customers you had at the start, so customers who joined during the period do not distort the rate.
Why is annual churn not 12 × monthly churn?
Each month’s churn applies to a smaller base, so the monthly figures compound rather than add.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.