Customer Retention Calculator
Estimate the share of a starting customer cohort that remains by the end of a period after excluding customers newly acquired during that period.
How to use this calculator
- Enter starting customers, new customers acquired, and total ending customers from the same cohort and period.
- Review the worked example for customer retention calculator and compare the inputs with your own units.
- Change one assumption at a time and recalculate if you need a second scenario.
Cohort retention rate
Retained customers = ending customers − new customers; retention rate = retained customers ÷ starting customers × 100.
- This conventional formula assumes the ending total includes new additions and that the cohort counts are comparable.
- The result is calculated from the values entered; the page does not independently verify assumptions, data quality or real-world suitability.
Worked examples
Retention over a month
A service starts with 500 customers, adds 60, and ends with 460 customers.
Retained = 460 − 60 = 400; retention = 400 ÷ 500 × 100 = 80%
The estimated retention rate is 80%.
Understanding the result
Separating new acquisitions from the ending total prevents new accounts from being mistaken for retained customers.
Reactivations, merged accounts, trial conversions and cohort definitions can change interpretation.
Important notes
Use the same counting rules and time window each month.
Displayed figures are rounded for readability. Preserve more precision during intermediate calculations and verify the labels and units before using the estimate.
Frequently asked questions
What does the Customer Retention Calculator show?
Separating new acquisitions from the ending total prevents new accounts from being mistaken for retained customers.
What assumptions should I check?
Use the same counting rules and time window each month.
Does this replace expert or authoritative guidance?
Reactivations, merged accounts, trial conversions and cohort definitions can change interpretation.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
- How to Calculate Percentage Change — Learn the percentage change formula, how to calculate increases and decreases, and why the original value matters.
- Percentage Change vs Percentage Difference — Understand the difference between percentage change and percentage difference, including when each formula is appropriate.
- Percentage — Understand what a percentage means, how percentages are calculated, and when to use a percentage calculator.
This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.