Churn Rate Calculator
Last updated: November 5, 2026
Calculate customer churn, retention and an approximate customer lifetime.
Monthly customer churn rate
—
- Churn during selected period: —
- Retention during selected period: —
- Approximate lifetime at monthly churn: —
On this page
Quick summary: Calculate customer churn, retention and an approximate customer lifetime.
Read the complete guide
Updated reference sections in this guide are in English.
What this calculator estimates
Calculate customer churn, retention and an approximate customer lifetime.
How to use it
Enter Customers at start of period; Customers lost during period; Period length. Select Calculate to update the results.
How the calculation works
Period customer churn = lost customers / customers present at the beginning. Retention is 1 minus that fraction. For a period of m months, the equivalent constant monthly churn is 1 - (1 - period churn)^(1/m). The illustrative lifetime is 1 / monthly churn in months.
Worked example: starting scenario
| Customers at start of period | 1000 |
|---|---|
| Customers lost during period | 40 |
| Period length | 1 month |
| Monthly customer churn rate | 4.00% |
|---|---|
| Churn during selected period | 4.00% |
| Retention during selected period | 96.00% |
| Approximate lifetime at monthly churn | 25.0 months |
Important limitations
This measures customer-count churn, not revenue churn. The lifetime illustration assumes an unchanging churn probability and is not a prediction of any particular customer's behavior. New acquisitions during the period are not added to the starting cohort. With no observed churn, a finite lifetime is not estimated.
An inferred monthly rate is not a monthly observation
For a multi-month period, the page solves (1 − monthly churn)^months = retained share. This differs from simply dividing total churn by months. Losing 19 of 100 starting customers over two months implies a constant monthly churn rate of 10%, because 0.9 × 0.9 = 0.81. The lifetime illustration assumes this same churn probability continues; it is not a customer-level forecast and does not account for changing cohorts.