Hong Life CalculatorsUnderstanding the customer retention rate calculator — concept and principle
The customer retention rate (CRR) shows what share of the customers you had at the start of a period were still customers at the end. It is a core health metric for subscription businesses, software, telecoms, gyms, agencies and any company with ongoing accounts, because keeping an existing customer is usually cheaper than winning a new one.
How it is calculated
- Retention rate = (customers at end − new customers acquired) ÷ customers at start × 100
- Churned customers = customers at start − (customers at end − new customers)
All three numbers must refer to the same period, for example one month, one quarter or one year.
The principle
The end-of-period count mixes two groups: customers who stayed and customers who joined during the period. Subtracting the new customers leaves only the survivors from the starting group. Dividing survivors by the starting count gives the share retained. Anyone in the starting group who is not among the survivors has left, which gives churn. Retention and churn rate always add up to 100%, since every starting customer either stayed or left. This version counts customers, not revenue, so a small and a large account weigh the same.
Worked example
- Inputs: 1,000 customers at start, 1,050 at end, 200 new customers.
- Survivors from the start: 1,050 − 200 = 850.
- Retention rate: 850 ÷ 1,000 × 100 = 85%.
- Churned customers: 1,000 − 850 = 150, a churn rate of 15%.
- Note that the customer base grew by 50 even though 150 customers left, because 200 joined.
How to read the result
Higher is better, but compare only like periods: a monthly rate of 95% means far more lost customers over a year than an annual rate of 95%. If monthly retention r stays constant, roughly r¹² of a starting group remains after a year (0.95¹² is about 54%). Good levels differ by industry and contract type; your own trend and cohort data are the most useful benchmark. If the base grows while retention falls, growth is masking a leak that will become visible when acquisition slows.
Common mistakes
- Forgetting to subtract new customers, which can push retention above 100%.
- Counting customers who joined and left within the period inconsistently.
- Comparing monthly and annual rates directly.
Frequently asked questions
What is the difference between retention rate and churn rate?
Churn rate is the share of starting customers who left; retention is the share who stayed. Here they add up to 100%.
Can retention be over 100%?
Customer retention cannot, if the inputs are correct. Net revenue retention can, because existing customers may upgrade.
Which period should I use?
Use the billing cycle for subscriptions (often monthly) and a longer period, such as a year, for slower purchase cycles.
Sources: P. Farris, N. Bendle, P. Pfeifer and D. Reibstein, Marketing Metrics, Pearson · F. F. Reichheld, The Loyalty Effect, Harvard Business School Press