Churn Rate
Quick Answer: Churn rate is the share of customers or revenue lost in a period; it directly affects LTV and the ROI of retention programs.
Churn rate is the percentage of customers or subscribers who stop using a product or service during a given period. It measures attrition and is a key driver of LTV and unit economics. Lower churn extends customer lifetime and improves the return on acquisition spend.
This page provides a structured explanation of churn rate and its effect on subscription economics, including formulas, examples, limitations, and comparisons with related financial metrics.
When to Use This Calculation
- Forecasting recurring revenue
- Evaluating retention ROI
- Stress-testing LTV models
Limitations of This Metric
- Churn definitions differ (logo vs revenue churn)
- Seasonality can distort short windows
- Cohort selection matters
What Is Churn Rate?
Churn rate measures customer or revenue attrition over a period, commonly used in subscription and SaaS businesses.
Formula
Customer churn (subscription context):
Churn Rate = (Customers Lost in Period / Customers at Start of Period) × 100
Revenue churn measures lost revenue rather than customer count. Monthly and annual churn are both used; annual churn is often derived from monthly churn assuming constant rate: Annual Churn ≈ 1 − (1 − Monthly Churn)12.
Example
A subscription business starts the month with 1,000 customers and loses 30. Churn rate = (30 / 1,000) × 100 = 3% monthly. At 3% monthly churn, the average customer lifespan is approximately 1 / 0.03 ≈ 33 months.
Relationship to LTV
Churn rate directly affects LTV. In the simplified LTV formula LTV = (ARPU × Gross Margin) / Churn, higher churn lowers LTV. A business with 2% monthly churn has roughly twice the LTV of one with 4% churn, all else equal. Reducing churn is often a high-leverage way to improve unit economics.
Relationship to ROI
Because churn affects LTV, it affects the return on customer acquisition. Higher churn means shorter customer lifetimes and lower total revenue per customer, reducing the effective ROI of marketing and sales spend. Payback period—how long until CAC is recovered—also depends on churn; see payback period.
Caveats
Churn can be measured as customer count or revenue. Voluntary churn (canceled) differs from involuntary (payment failure). Cohort analysis is often needed to understand how churn varies by acquisition cohort. Seasonal or one-time events can distort period-over-period comparisons.