Churn
Definition
Churn (short for customer churn) is the rate at which customers stop using a product or service during a given period.
- Opposite of retention.
- A critical metric in SaaS, subscription businesses, telecom, finance, and apps.
Types of Churn
- Customer Churn → % of customers lost. $\text{Customer Churn Rate} = \frac{\text{Customers lost in period}}{\text{Customers at start of period}} \times 100$
- Revenue Churn → % of revenue lost (can differ from customer churn if big clients leave).
- Voluntary vs Involuntary Churn
- Voluntary → customer cancels service by choice.
- Involuntary → caused by failed payments, expired cards, etc.
Examples
- SaaS business
- Start of month: 1,000 paying users.
- End of month: 950 users.
- Customers lost = 50 → Churn rate = $50 / 1000 = 5\%$.
- Mobile app
- If 40% of new users uninstall the app within 30 days → 30-day churn = 40%.
Why Churn Matters
- Direct revenue impact → Losing customers = losing recurring revenue.
- Growth limit → Even with high acquisition, high churn can cancel out growth.
- Retention is cheaper → It usually costs 5–7x more to acquire a new customer than to keep an existing one.
In ML / Analytics
- Churn Prediction Models → predict which users are likely to churn based on behavior (logins, purchases, complaints).
- Churn Reduction Strategies:
- Personalized offers or discounts.
- Better onboarding experience.
- Customer support interventions.
Churn vs Retention
- Retention Rate = % of users who stay.
- Churn Rate = % of users who leave.
- If monthly churn = 5% → retention = 95%.
Summary
Churn = % of customers or revenue lost over a period.
- Key business metric, especially in subscriptions.
- Opposite of retention.
- Predicting & reducing churn is critical for sustainable growth.