SaaS & retention
Customer Churn Rate Calculator
Measure the share of customers present at the start of a period who leave during that same period.
Use this for logo or customer loss from a starting cohort. Use net revenue retention when account sizes, downgrades, and expansion matter.
What the result means
This is the percentage of the opening customer cohort lost, without offsetting new acquisitions. The period matters: monthly and annual churn are not interchangeable or linearly convertible.
The formula
(Starting-cohort customers lost / customers at period start) * 100
Results are displayed to at most two decimal places. Calculations use the unrounded inputs.
A worked example
Put the formula to work
- Customers at period start (customers)
- 500
- Starting-cohort customers lost (customers)
- 20
Customer churn rate for the selected period: 4%
Losing 20 of the 500 customers present at the start of a month gives 4% monthly customer churn.
How to use this calculator
- Set the period and a rule for when cancellation counts as churn.
- Freeze the opening customer cohort before adding new signups.
- Count losses only from that cohort.
- Divide cohort losses by the opening count and label the period.
Why this number matters
A cohort-based customer loss rate keeps strong acquisition from masking deterioration in existing-customer retention.
Input definitions
- Customers at period start (customers)
- Active paying customers at the beginning of the chosen period; exclude customers acquired afterward. Must be greater than zero.
- Starting-cohort customers lost (customers)
- Customers from that opening cohort who meet your churn definition during the period; cannot exceed the opening count.
Assumptions and limitations
- Weights all customers equally regardless of recurring revenue.
- Reactivations, pauses, and failed payments need a consistent policy.
- A short-period rate does not automatically predict long-run lifetime.
Methodology
The default result and worked example use the same calculation functions as the interactive tool. The formula cannot verify the quality or scope of your source data.
Read our calculation methodology
Last updated .