```html
Retention and Churn Metrics Calculator
Retention and Churn Metrics Calculator
Churn Rate
Churned Users:
Starting Subscribers:
Calculate Churn Rate
Customer Acquisition Cost
Marketing Spend:
New Subscribers:
Calculate Acquisition Cost
Subscriber Growth Ceiling
New Subs Per Month:
Monthly Churn Rate:
Calculate Growth Ceiling
Payback Period
Acquisition Cost:
Subscription Price:
Retention Rate (monthly):
Calculate Payback Period
```