What is Churn Rate?

Churn rate measures how fast customers leave. If you start a month with 100 customers and 5 cancel, your monthly customer churn is 5%. It's the leak in the bucket — every new customer you pour in has to first replace the ones draining out.

Churn is the quiet killer of subscription businesses. A company can be signing up customers furiously and still shrink if churn is high enough. Controlling it is usually cheaper and more powerful than acquiring new customers.

Two kinds of churn

There are two flavors, and the difference matters. Customer churn counts how many accounts leave. Revenue churn counts how much money leaves — which can differ sharply if your big and small customers behave differently.

• Customer churn: lost customers ÷ total customers at the start of the period.
• Revenue churn: lost recurring revenue ÷ recurring revenue at the start.
• Net revenue churn can go negative (good!) when existing customers upgrade enough to outweigh losses.

Why churn matters for validation

Churn is the clearest signal of whether you've built something people truly need. Low churn means customers find ongoing value and your LTV is high. High churn means you're solving a one-time problem with a recurring fee, or the product isn't sticky — a warning sign no amount of marketing can fix. Watch it by cohort to see if newer customers stay longer than older ones did.