% of customers lost per period. The Churn Rate Calculator takes customers at the start of the period, customers lost during the period and returns customer churn rate plus implied average customer lifetime, annualized churn (if the period is a month). Results update as you type, and the formula is shown under the result so you can repeat it in your own spreadsheet.
Startup metrics are about the efficiency of growth: how much it costs to win and keep customers, how fast recurring revenue compounds, and how long the cash lasts. Investors read these numbers before they read the pitch. Use the worked example below to check the maths against your own figures.
How the Churn Rate Calculator works
A 4% monthly churn means the average customer stays about 25 months and nearly 39% of customers leave in a year. Churn is the single biggest drag on subscription growth.
Worked example
With the example values (customers at the start of the period of 1000, customers lost during the period of 40), the customer churn rate is 4%; implied average customer lifetime 2 years 1 month, annualized churn (if the period is a month) 38.73%. Change any figure above and the result updates immediately; use Copy results to paste the summary into a note or email.
Related Calculators
Frequently Asked Questions
How is customer churn rate calculated?
churn rate = customers lost ÷ customers at the start; lifetime ≈ 1 ÷ churn.
Which figures do I need?
Customers at the start of the period, customers lost during the period. Take them from the same period and the same set of accounts or reports so the ratio is consistent, and check the example values as a guide to the units expected.
What do investors consider healthy?
Common benchmarks: LTV:CAC above 3, CAC payback under 12–18 months, net revenue retention above 100%, monthly churn under 2% for SMB and under 1% for enterprise, and at least 12–18 months of runway.
