Churn Rate & Retention Calculator
Customer churn and retention per period from customers at start, lost and gained, with annualised rate, implied lifetime, and optional revenue churn and NRR.
How fast customers leave, what that means over a year and for the average lifetime, and — with MRR figures — whether the revenue base is shrinking or growing on its own.
Example: 1,000 customers at the start of the month, 50 lost, 120 gained: 5 % churn, 95 % retention, 46 % annualised churn, an implied lifetime of 20 months, and 1,070 customers at month end.
Lost over start.
Then compound it.
The definition used, why annualised churn is not twelve times monthly churn, and the difference between customer and revenue churn.
Churn and retention
Churn for a period is the customers lost during it divided by the customers you had at its start; retention is the rest. New customers gained in the period are not in the denominator — they had no chance to churn yet — which is why start, lost and gained are entered separately and the end count is derived. Over several periods the average is total lost over total start (customer-weighted), and the page checks that each period starts where the last one ended.
Annualising and lifetime
Retention compounds: keeping 95 % each month keeps 0.95¹² = 54 % over a year, so annual churn is 46 %, not 60 %. The page uses 1 − (1 − c)ⁿ with n periods per year. The implied customer lifetime is 1 ÷ churn periods — the average of a geometric decay — and is the figure LTV formulas use; it assumes the churn rate stays constant, which early-life churn often violates, so treat it as a first estimate.
Revenue churn and net revenue retention
Counting logos treats a small and a large customer alike. With the MRR at the start of a period, the MRR lost with churned customers, and expansions and contractions among those who stayed, the page also shows revenue churn (lost ÷ start) and net revenue retention, (start + expansion − contraction − lost) ÷ start — above 100 % means the existing base grew without any new customers. No benchmark is given: what counts as good depends on segment and price point. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- Customer churn, retention and net revenue retention as commonly defined in SaaS metrics guides (e.g. SaaS Capital, David Skok’s "SaaS Metrics 2.0") — definitions only; no benchmark adopted
Last reviewed 19 September 2026. How results are checked: How we verify.