Customer Retention Rate (CRR) measures how well a business holds onto its existing customers over a defined period.
CRR = (End Customers - New Customers) / Start Customers × 100
Why the Formula Isolates Retention
By subtracting new customers from the end count, you isolate how many of the original customers are still active. New customer acquisitions don't mask underlying churn.
Example: Start with 500 customers, end with 490, acquire 40 new → Retained = 490 − 40 = 450. CRR = 450/500 = 90%.
Why Retention Is the Most Important SaaS Metric
At 90% monthly retention, a business retains ~28% of customers after 12 months. At 95%, it retains ~54%. The compound effect is enormous.
Revenue implications: - 2% monthly churn = ~22% annual churn → modest growth requires constant acquisition - 5% monthly churn = ~46% annual churn → the business is on a treadmill
Improving Retention
- Customer success: proactive check-ins before renewal risk peaks
- Onboarding: time-to-value is the single biggest retention predictor in the first 90 days
- Product engagement: users who activate the core feature within 7 days retain at 2× the rate of those who don't
- Exit interviews: understand why customers churn to address root causes