SaaS Metrics

Churn Rate Calculator

Calculate customer churn rate from lost customers and starting customers.

Churn rate = Lost customers / Starting customers × 100%

What this calculator does

Calculate customer churn for one defined period and, only when that period is one month, estimate retention after 12 identical months.

Scope, period, and currency

This page runs a local formula from user-entered values. The country/currency selector changes money symbols and formatting only: it does not perform live or historical FX conversion or automatically change contract, tax, accounting, or regulatory rules. Convert all amounts into one currency first and keep periods and metric definitions consistent.

Formula variables

S: Customers active at the start of the period.
L: Those starting customers lost during the period.

Formula and worked example

Formula: Churn = L ÷ S × 100%; retained starting customers = S − L; monthly-model annual retention = (1 − L ÷ S)^12.

Recalculation: 18 losses from 620 starting customers gives 2.90% period churn and 602 retained. If the period is one month and churn stays constant, modeled 12-month retention is 70.22%.

Model assumptions

Lost customers come from the opening population and do not exceed it.
Annualized retention is meaningful only when the input period is one month.
New customers, revenue churn, reactivations, and cohort mix are outside the formula.

Reading the result and model boundary

The primary result is logo/customer churn, not revenue churn.
Treat annualized retention as a scenario, not a forecast.

The model measures starting-customer logo churn and does not reconstruct subscription events.

How to use it

Define the customer population and period.
Count only starting customers that churned under that definition.
Use annualized retention only for a monthly period.

Common incorrect uses

Entering quarterly churn and reading the annualization as monthly.
Allowing losses to exceed starting customers.
Mixing customer churn with MRR or revenue churn.

Suggested verification workflow

Freeze the period and cohort definition.
Calculate period churn.
Compare with cohort and revenue-retention reports.

FAQ

Can lost customers exceed starting customers?

No. That indicates a population or period-definition error.

Is annualized retention always valid?

No. The page's 12-power scenario assumes the entered churn is monthly and remains constant.

Does currency selection affect churn?

No. Churn has no currency conversion; locale controls do not change the formula.

Method and review boundary

Results are calculated locally in the browser from the formula shown on this page. The tool does not retrieve live rates, quotes, approvals, or billing data. Last reviewed: July 24, 2026.

Use the result for first-pass estimates, scenario comparison, and question preparation; it is not financial, investment, tax, accounting, or legal advice.

Authoritative sources and notes

Customer churn rate methodology - ChartMogul
Gross churn measurement - Stripe

Sources checked July 24, 2026. Rates, product rules, and official guidance can change; verify them again before a formal decision.