Customer Retention & Churn Calculator

How the customer retention & churn calculator works

Retained starting customers = ending active customers − new customers still active at the end. Starting-cohort losses equal starting customers less those retained. The retention and churn percentages divide those two counts by starting customers, so their sum is 100% whenever a positive starting population exists.

Use the same customer definition and reporting period for every count. The new-customer input is an ending snapshot subset, not gross acquisitions during the period; this prevents a new customer who both joined and left from being misclassified as a loss from the original cohort. Counts must be whole and nonnegative.

The retained original cohort cannot exceed its starting size, and new active customers cannot exceed total ending customers. Reactivations and population transfers need consistent classification before entry. Zero starting customers gives undefined percentages. This tool measures customer counts, not net revenue retention, expansion, statistical churn probability or expected lifetime.

Worked example

Starting with 1,000 customers, ending with 1,050 and identifying 100 new customers still active at the end leaves 950 retained from the original cohort. Fifty were lost, giving 95% retention and 5% churn. Net active customer growth is 50. If ending customers were 1,000 with the same 100 new active customers, retention would be 90%.

Sources and assumptions

The source material explains the underlying calculation or pricing structure. Entered prices, costs, schedules and scenario choices are your assumptions; this tool does not obtain supplier quotes or predict actual results.

• Stripe: retention and churn calculation conventions