Use the calculator with period values
Choose Customer churn (count) or Revenue churn (amount), then enter starting and lost values for the same period. Add gained and ending values when you have them. The Period choice labels the result and download; it does not convert or normalize the values.
Enter values and calculate
- Choose Customer churn (count) or Revenue churn (amount) from Churn type.
- Choose a label from Period: Monthly, Quarterly, Annual, or Custom period.
- In Revenue churn mode, choose Currency symbol: $, €, £, ¥, or None. This changes the display label only; no conversion is applied.
- Enter Starting value and Lost value. Starting value must be greater than 0. Lost value must be numeric and 0 or more, and it cannot exceed Starting value.
- Optionally enter Gained value and Ending value. Each supplied value must be numeric and 0 or more. A blank Gained value is treated as 0.
- Select Calculate churn.
- Select Reset to clear the form and start again.
If Starting value or Lost value is blank or invalid, if an optional value is invalid, or if Lost value exceeds Starting value, the calculator shows an error and keeps the result hidden.
Review the result and formulas
After a successful calculation, the result shows gross churn rate, retention rate, net churn rate, and net retention rate. It also includes the formulas, an assumptions table, and a disclaimer:
Gross churn rate = Lost / StartingRetention rate = 1 - Gross churn rateNet churn rate = (Lost - Gained) / StartingNet retention rate = 1 - Net churn rateGrowth rate = (Ending - Starting) / Starting
When Ending value is blank, the calculator uses Starting - Lost + Gained as the implied ending value, including for growth rate. When you supply an Ending value, that value drives growth rate even if it differs enough to trigger a cross-check warning. The calculator compares a supplied ending value with the implied value and may show a warning.
Copy or download the result
Select Copy result to copy the displayed result when clipboard access succeeds. If copying fails, the tool displays an error asking you to select and copy manually. Select Download result (.txt) to download a text file named churn-rate-calculator-result.txt.
Limitations and calculator data handling
- The calculator performs its arithmetic locally in
script.jsfrom the values you enter. - It does not fetch customer or revenue records from a CRM, billing system, or live system.
- It uses the figures you enter and does not look up live rates or external data.
- The current implementation accepts decimal customer values and does not define a formal whole-customer integer rule.
- The calculation does not account for your definitions of a customer or churn event, cohort differences, contract terms, or seasonality.
Frequently Asked Questions
How is churn rate calculated?
Gross churn rate is the number or amount lost during a period divided by the starting number or amount: Lost / Starting, shown as a percentage. Net churn rate subtracts what you gained during the same period first: (Lost - Gained) / Starting, so it can be negative if gains outpace losses.
What is the difference between customer churn and revenue churn?
Customer churn measures the count of customers or accounts lost, while revenue churn measures the dollar (or other currency) amount of revenue lost. The same formulas apply to both - only the unit changes. This tool lets you switch between the two.
Why does the tool ask for an ending value if it can be calculated?
The ending value is optional. If you leave it blank, the tool computes it as starting minus lost plus gained. If you enter your own recorded ending figure, the tool compares it to the implied value and flags a warning if they do not match, which can help catch a data entry mistake or an untracked change.
Does this tool fetch my actual customer or revenue records?
No. It calculates from the starting, lost, gained, and ending figures you type in. It does not connect to a CRM, billing system, or fetch live records; the calculator arithmetic runs locally in your browser.
Is this a substitute for financial or business advice?
No. This tool performs transparent arithmetic on the figures you provide. It is not financial, accounting, or business advice, and it does not account for cohort differences, seasonality, contract terms, or how you define a "customer" or "churn event" in your own business.