Churn Rate Calculator
Enter how many customers you started with and how many you lost to get your churn rate, retention rate, and average customer lifespan.
The metric that quietly decides growth
Churn is the rate at which customers leave, and for any subscription or recurring-revenue business it's the number that quietly caps your growth. Even a great acquisition engine stalls if the bucket is leaking. Enter the customers you began the period with and how many you lost, and this calculator returns your churn rate, the matching retention rate, and the average lifespan a customer implies at that pace.
That lifespan figure is the bridge to lifetime value: at 4% monthly churn the average customer stays 25 months, which tells you how much you can afford to spend acquiring them. Track churn each period and watch the trend — a small, steady reduction compounds into a much larger customer base over time.
How it's calculated
Churn rate = (customers lost ÷ customers at start) × 100. Retention = 100 − churn. Average lifespan = 1 ÷ churn rate (as a decimal). All computed live in your browser.
Frequently Asked Questions
How is churn rate calculated?
Divide the number of customers lost during a period by the number you had at the start, then multiply by 100. Losing 20 of 500 customers in a month is a 4% monthly churn rate.
What is the difference between churn and retention?
They are two sides of the same coin. Retention rate is 100% minus the churn rate. A 4% monthly churn means 96% monthly retention.
What does average customer lifespan mean?
If churn is steady, the average customer stays for 1 ÷ churn rate periods. A 4% monthly churn implies an average lifespan of 25 months.
Is this calculator free and private?
Yes. It runs entirely in your browser — no account needed and nothing is uploaded.
Retention, pricing, and growth strategy for service businesses and SaaS.