Churn

What it means

Churn is the share of customers or revenue lost over a period. Customer churn counts heads, revenue churn counts euros, and the two can diverge: losing one large client barely moves the headcount and moves MRR a lot.

It is mostly used for subscriptions and recurring services (SaaS, bookkeeping, maintenance) where revenue renews every month. Retention is the same number read from the other side.

Churn is often confused with falling turnover. Revenue can grow despite high churn if new customers outweigh departures, and fall with zero churn if remaining clients simply buy less. That is why gross churn, which counts departures and downgrades, is kept apart from net churn, which also credits expansion from the customers who stay.

How it works in practice

Churn decides whether acquiring customers pays at all: in unit economics lifetime value is margin times average relationship length, which is churn in disguise. High acquisition cost with high churn never works out.

The data sits in CRM and in billing: who was not invoiced this month but was last month. Linking billing to CRM is what turns churn into a measurable KPI rather than an impression.

In services such as bookkeeping, departures tend to cluster at a few moments: after the annual closing, after a price change, or when the contact person changes. It pays to track churn month by month and to record the reason at every offboarding. A few dozen entries are enough to see what can actually be influenced.

What to watch out for

Do not mix a temporary pause with a departure, and never quote churn without stating the period. Monthly and annual churn are not comparable either - 3 % a month is roughly 31 % a year, not 3 %.

Churn measured only from billing misleads when payment cycles are mixed. A customer who paid a full year up front looks like a departure in every month without an invoice. In that case churn must be counted from active contracts, not from invoices issued, or the numbers jump about and management chases a problem that does not exist.