The rate at which customers, or their revenue, leave over a period. The single number that most determines what growth costs, and one of the easiest to define into looking better.
Acquisition is a tap; churn is the hole in the bucket. Businesses report the tap with pride and define the hole with creativity, which is why the churn definition deserves as much scrutiny as the churn number.
Last reviewed 3 July 2026 · Free and ungated
Operators who have run subscription businesses can challenge the churn definition before it prices a decision.
Get independent perspectivesChurn is the proportion of customers (logo churn) or revenue (revenue churn) lost over a period, usually monthly or annually. The two diverge by design: losing ten small accounts while keeping one large one produces high logo churn and low revenue churn. Gross revenue churn counts only losses; net figures offset them with expansion from surviving customers, which is a different metric answering a different question.
Churn compounds. Five per cent monthly churn sounds survivable and means losing nearly half the customer base within a year, so acquisition spend is refilling a draining pool before it grows anything. Churn also sets the ceiling on customer lifetime value, and with it the maximum a business can rationally pay to acquire a customer; a churn assumption one point too optimistic flows straight through valuation models and marketing budgets. In diligence, cohort-level churn is where growth stories go to be tested, because a rising top line can hide worsening retention for a surprisingly long time.