METHOD & GUIDANCE
How this calculation works
Enter figures from the same period and on a consistent sales tax-inclusive or sales tax-exclusive basis. Tool IQ recalculates every output immediately; nothing you enter is saved or sent to us.
How to use the result
Measure customer and revenue churn for the same cohort and period, then compare retention work with the cost of replacing lost customers.
Worked example
Losing 50 of 1,000 opening customers is 5% customer churn and 95% retention before considering 80 newly acquired customers.
Common mistakes
- Including new customers in the opening denominator.
- Mixing monthly losses with an annual starting base.
- Assuming customer churn and revenue churn are identical.
Frequently asked questions
Is this calculator free?
Yes. It requires no account and stores no calculation inputs.
Can I use the answer for a formal filing?
No. It is a planning estimate, not accounting, tax, legal or investment advice. Confirm material decisions with a qualified professional.
Should I include sales tax?
Use a consistent basis throughout. Businesses that recover input tax commonly model net figures; consumer-facing prices are often considered gross.
Continue the decision
- Customer Acquisition Cost Calculator — Compare acquisition cost with estimated customer value.
- Revenue Growth Calculator — Measure growth and project a future revenue scenario.
Method reviewed 26 July 2026. Figures are illustrative and calculated locally in your browser.