Most "churn rate" answers stop at one formula: customers lost divided by customers at the start. That formula is fine until your customer count is changing fast, you have multiple cohorts, or your customers don't all pay the same amount. Which is to say, it's fine if you have one customer.
Real businesses need to know which method to use, when, and what each one tells them. Here are the 4 methods, ranked by sophistication.
For a faster path to insight: take the Churn Health Check and it'll tell you not just your churn rate but whether you're measuring it correctly in the first place.
Method 1: Simple churn rate (the one everyone uses)
Formula: Customers Lost / Customers at Start of Period
Example: You started March with 1,000 customers. Lost 50 during March. Simple churn rate: 50 / 1,000 = 5%.
When to use it: Quick board updates, casual benchmarking, situations where your customer count is stable. It's the easiest to calculate and explain.
Where it fails: When your customer count is growing fast. If you started March with 1,000, lost 50, but added 300 new customers, the 50 lost happened among an effective base much larger than 1,000. Simple churn overstates your actual churn rate during high-growth periods.
Method 2: Average churn rate
Formula: Customers Lost / ((Customers at Start + Customers at End) / 2)
Example: Started March with 1,000. Ended with 1,250. Lost 50. Average: 50 / 1,125 = 4.4%.
When to use it: When your customer count is changing meaningfully during the period. Most growing SaaS companies should default to this over the simple method.
Where it fails: Still doesn't account for the fact that newly-acquired customers had less time to churn during the period. The 300 customers acquired on March 30th had only 1 day to churn, but they're in the denominator as if they had a full month.
Method 3: Cohort-based churn rate (the most accurate)
Formula: For each signup cohort, track what % churns over time. Then aggregate or compare cohorts.
Example: Customers who signed up in January 2026 had 950 active by month 6, started at 1,000. Cohort retention at month 6: 95%. Cohort churn over 6 months: 5%.
When to use it: Whenever you need real insight, not just a number for a slide. Cohort analysis reveals patterns that blended numbers hide entirely.
What it shows you:
- Whether retention is improving or declining over time (compare recent cohorts to old ones)
- When in the customer lifecycle churn happens (first 30 days vs month 12)
- Which acquisition channels produce stickier customers
- Whether changes in your product/pricing actually moved retention
The cost: More work to set up. Requires you to track each cohort separately. Tools like Amplitude, Mixpanel, ChartMogul, and Baremetrics can do this automatically.