Calculate churn rate

Measure the share of an opening customer cohort that leaves during one month and compound the remaining share across a year.

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ToolChurn Rate Calculator
Input
Output
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How it works

Monthly churn divides customers lost by customers present at the start, and monthly retention is the remaining fraction. Annual retention raises that monthly retention factor to the 12th power, so a 5% monthly loss leaves 54.04% after a year rather than implying a simple 60% loss.

Formula
monthly churn = customers lost ÷ customers at start × 100
annual retention = (1 − monthly churn)¹²
  • Annualisation treats the entered period as a month and assumes the same retention factor repeats twelve times.
  • New customers acquired during the period are excluded because this is a loss rate for the opening cohort.

Worked example

200 customers at the start, 10 lost
A monthly churn figure, annualised by compounding
Input
											Customers at start: 200
Customers lost: 10
Output
												Monthly churn rate percent: 5
Monthly retention rate percent: 95
Annualised churn rate percent: 45.96
Annualised retention rate percent: 54.04
Customers remaining: 190

When to use this

SaaS subscriptions, mobile-app cancellations, and recurring membership cohorts use opening-customer retention to compare monthly losses and forecast one-year survival.

Edge cases

  • A starting cohort of 0 has no denominator, so processing stops instead of reporting 0% churn.
  • Losing more customers than existed at the start is rejected as an impossible cohort.
  • Monthly churn of 100% produces 0% annual retention; compounding never creates a negative customer share.