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Customer Churn & Lifetime Estimate Calculator

Calculate customer loss per period and a simple constant-churn lifetime estimate.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Edit a calculated value to solve backwards, or lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Results are estimates for planning and education. Confirm rates, taxes, fees, and legal requirements with the relevant institution or a qualified professional before making a financial decision.

Formula and method

Divide customers lost during the period by customers at its start. The reciprocal of that churn fraction estimates lifetime in periods under a constant-churn model.

Churn (%) = customers lost ÷ starting customers × 100; lifetime = 100 ÷ churn (%)

Worked example

Enter these known values and leave the other values blank.

Customers at start of a period
1000
Customers lost during period
50
Churn rate
5 %
Customer lifetime
20 periods

Assumptions and limitations

  • Inputs describe one consistent reporting period. Review the formula and counting conventions before comparing results.

Common questions

Is the lifetime estimate measured in months?

Its unit follows the churn period. Monthly churn gives months; annual churn gives years. A constant rate is an assumption, not a forecast for every customer.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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