Churn rate measures the percentage of customers who stop using a product or service during a given time period, typically calculated monthly or annually. For subscription-based businesses, this metric reveals how quickly a company is losing its customer base and directly impacts long-term revenue projections and valuation.
The basic calculation divides the number of customers lost during a period by the total customers at the start of that period. A SaaS company with 1,000 customers at month start that loses 50 customers shows a 5% monthly churn rate. Companies often track both customer churn (logo churn) and revenue churn, since losing a high-value enterprise client impacts financials differently than losing several small accounts.
Why It Matters
Churn rate directly determines whether a subscription business can achieve sustainable growth. A company with 5% monthly churn loses half its customer base every 14 months, requiring aggressive acquisition just to maintain revenue levels. Most venture-backed SaaS companies target annual churn below 10% for small businesses and under 5% for enterprise customers. High churn signals product-market fit problems, poor customer service, or pricing issues that will eventually cap growth regardless of marketing spend. Investors scrutinize this metric because customer acquisition costs become worthless if those customers leave before generating sufficient lifetime value.
Example
A meal kit delivery startup raises a Series A with 50,000 subscribers and 3% monthly churn. While this seems modest, the company loses 1,500 customers monthly—18,000 annually. To grow from 50,000 to 100,000 subscribers in one year, they must acquire 68,000 new customers just to offset churn and achieve their target. If customer acquisition cost runs $80 per subscriber, the company needs $5.4 million purely to replace churned customers before adding a single net new subscriber. When investors model the business at a $50 million valuation, they discover that 15% churn (not the claimed 3%) renders the unit economics unsustainable, forcing a down round or closure within 18 months.