Calculate customer churn rate for a SaaS business and estimate retention risk. This churn calculator shows monthly churn, retained customers, annualized churn pressure, and how many new customers are needed to recover losses.
Enter the number of customers at the start of the period, customers lost, new customers added, and average monthly revenue per customer.
The calculator separates customer churn from net growth so new sales do not hide retention issues.
Churn rate measures the share of existing customers lost during a period. High churn weakens LTV, increases replacement pressure, and makes growth more expensive.
Do not include newly acquired customers in the churn denominator when measuring cohort churn.
If a SaaS starts with 1,000 customers and loses 45, monthly churn is 4.5%. If 80 new customers are added, net customer growth is 35.
Divide customers lost during the month by customers at the start of the month, then multiply by 100.
Lower is better. Many SaaS teams aim for low single-digit monthly churn, especially in B2B subscriptions.
At minimum, you need to add as many new customers as you lost. More are needed if you want net growth after churn.
Higher churn shortens average customer lifetime, which lowers LTV and makes acquisition spending harder to recover.
For standard customer churn, use the starting customer count as the denominator so new sales do not distort retention.
| Metric | Use |
|---|---|
| Customer churn | Percentage of starting customers lost. |
| Net growth | New customers after replacing losses. |
| Revenue lost | MRR lost from churned customers. |
| Annualized risk | Approximate pressure if monthly churn continues. |