Enter how many customers you started the period with and how many left. You get churn and retention rates, the annualized figure, and average customer lifespan.
How it works
Churn rate is the share of customers who leave in a period: customers lost divided by customers at the start. Its mirror is retention. Because monthly numbers compound, a "small" 5% monthly churn quietly becomes 46% of customers gone in a year, which is why the calculator annualizes it for you.
Formulas: Churn = Lost / Start x 100 · Annualized = 1 - (1 - monthly churn)¹² · Avg lifespan = 1 / churn.
Advanced options add average revenue per customer, turning the customers you lost into the revenue you lost.
Everything runs in your browser. Your numbers are never sent to a server, and there is no signup or limit. Your last entries are remembered locally so the calculator is ready next time.
Frequently asked questions
How do I calculate churn rate?
Divide customers lost during the period by customers at the start of it. Starting a month with 500 customers and losing 25 is a 5% monthly churn (95% retention). Count only existing customers who left, not new signups that also arrived.
What is a good churn rate?
For SaaS, 3-8% monthly is common for SMB products while good enterprise products run under 1% monthly; consumer subscriptions often churn faster. More useful than any benchmark: track your own trend, and translate churn into lifespan, at 5% monthly your average customer stays about 20 months.
Why does monthly churn look so much worse annualized?
Because it compounds: each month you lose a slice of an already-shrunken base. 5% monthly is not 60% yearly but 1 - 0.95¹² = 45.96%. The calculator does this conversion whenever the period is monthly.
How does churn relate to customer lifetime value?
Average lifespan is roughly 1 / churn (20 periods at 5%), and LTV is revenue per period x lifespan x margin. Cutting churn from 5% to 4% extends lifespan from 20 to 25 months, a 25% LTV lift with zero new marketing. Our LTV Calculator models this directly.
What does the revenue-lost figure show?
Turn on Advanced options and enter average revenue per customer for the period; the calculator multiplies it by the customers lost, putting a currency figure on the leak, usually the fastest way to justify retention work.