Customer Churn Calculator
Customer Churn Calculator divides customers lost during a period by customers present at the start. The result describes logo churn under a simple cohort definition. It does not measure revenue churn, net revenue retention, reactivations, customer additions, partial cancellations, or whether every account should carry equal weight.
Runs locally — files stay on your deviceWhat is customer churn if 8 of 200 starting customers leave?
Customer churn is 4%.
Formula: 8 ÷ 200 × 100 = 4%
Logo churn follows the starting customer cohort
Customer churn rate = customers lost during the period ÷ customers at the start × 100. New customers acquired during the period do not belong in the starting denominator.
How it works
Choose a period and define active customer and cancellation consistently. Enter the starting cohort and losses from that cohort, then state whether the metric is monthly, quarterly, or annual.
Key concepts
Logo and revenue churn answer different questions
Losing one large customer and one small customer counts equally in logo churn but not in revenue churn.
Period length changes interpretation
Four percent monthly churn is not equivalent to four percent annually.
When to use it
- Calculate simple logo churn for one period.
- Check a cohort-based cancellation percentage.
- Compare consistently defined periods.
When not to use it
- Do not substitute customer churn for revenue churn.
- Do not place newly acquired customers in the starting base.
- Do not compare monthly and annual churn percentages directly.
Worked examples
Monthly churn
- Input
200 starting customers; 8 lost- Expected output
4%
Eight is four percent of the starting cohort.
New acquisitions
- Input
200 start; 8 lost; 20 new- Expected output
Churn still 4%
New customers affect ending count, not losses from the starting cohort.
No starting customers
- Input
0 start; 2 later losses- Expected output
Undefined
There is no starting base for the ratio.
Common mistakes
Dividing by ending customers
Acquisition and loss are mixed. Correction: Use the starting cohort.
Subtracting new customers from losses
That produces net customer change, not churn. Correction: Report acquisition separately.
Comparing unequal periods
Exposure time differs. Correction: Use consistent periods or a retention model.
Best practices
- Document active-customer and churn definitions.
- Report period and starting cohort size.
- Review logo churn with gross and net revenue retention.
Related operations and differences
MRR to ARR Calculator
Choose MRR to ARR Calculator when you need to annualize monthly recurring revenue.; use Customer Churn Calculator specifically for churn.
Burn Rate Calculator
Choose Burn Rate Calculator when you need to estimate average monthly cash burn.; use Customer Churn Calculator specifically for churn.
Business Runway Calculator
Choose Business Runway Calculator when you need to estimate how many months current cash can cover.; use Customer Churn Calculator specifically for churn.
Gross Profit Calculator
Choose Gross Profit Calculator when you need to calculate gross profit and gross margin.; use Customer Churn Calculator specifically for churn.
Markup Calculator
Choose Markup Calculator when you need to calculate markup from cost and selling price.; use Customer Churn Calculator specifically for churn.
Profit Margin Calculator
Choose Profit Margin Calculator when you need to calculate profit as a percentage of revenue.; use Customer Churn Calculator specifically for churn.
Limitations and privacy
- The result is a simplified management estimate, not accounting, tax, legal, or investment advice.
- Reactivations, partial churn, acquisitions, contracts, and revenue weighting are not modeled.
- Starting customers must be positive.
Business figures are calculated locally in this browser and are not uploaded.
Frequently asked questions
What is customer-churn formula?
Customers lost ÷ customers at period start × 100.
Do new customers reduce churn?
No. They affect net growth, not losses from the starting cohort.
Is customer churn the same as revenue churn?
No. Logo churn weights every customer equally.
Can I compare monthly with annual churn?
Not directly; period length materially changes interpretation.