Subscription Box & MRR Retention Calculator
See how churn, new signups, and acquisition cost shape your recurring revenue and monthly profit.
How the Subscription MRR & Retention Calculator Works
A subscription business is a leaky bucket. Every month some subscribers cancel, and new signups have to refill the bucket just to keep the count steady. Churn decides how long each customer stays, how much each one is worth, and how large your subscriber base can ever get.
Enter your starting subscribers, monthly price, cost to fulfill one box, new subscribers per month, monthly churn rate, and the cost to acquire each new subscriber. The tool projects your MRR and subscriber count one month ahead, the steady-state ceiling your base will drift toward, the average subscriber lifetime, and customer lifetime value. It also shows your net monthly profit after subtracting acquisition spend and compares LTV with CAC.
Key Formulas Behind This Tool
- Gross Profit per Box: Subscription Price - COGS and Fulfillment per Box
- Net Monthly Profit: (Starting Subscribers x Gross Profit per Box) - (New Subscribers x CAC)
- Subscribers After This Month: Starting Subscribers x (1 - Churn Rate) + New Subscribers
- Net MRR After This Month: Subscribers After This Month x Subscription Price
- Steady-State Subscriber Ceiling: New Subscribers per Month / Churn Rate
- Average Subscriber Lifetime (months): 1 / Churn Rate
- Customer Lifetime Value (LTV): Gross Profit per Box / Churn Rate
- LTV to CAC Ratio: LTV / CAC
Frequently Asked Questions (FAQ)
What is MRR?
MRR (monthly recurring revenue) is the predictable revenue you collect each month from active subscribers, which is subscribers multiplied by the monthly price. This tool shows where it lands next month after churn and new signups.
What is the steady-state subscriber ceiling?
It is the subscriber count at which the people you lose to churn each month equal the people you add. It equals new subscribers per month divided by the monthly churn rate. Without more acquisition or lower churn, your base trends toward this number.
How is average subscriber lifetime calculated?
It is one divided by the monthly churn rate. At 8% monthly churn, the average subscriber stays about 12.5 months. At 0% churn the lifetime has no limit, so the tool shows N/A.
How is LTV calculated here?
LTV is the gross profit you earn per box (price minus COGS and fulfillment) multiplied by the average lifetime in months. Using profit instead of revenue gives a stricter and more useful number for judging how much you can pay to acquire a subscriber.
Why can the tool show a loss but still a blue status?
Subscription businesses often spend more on acquisition than the first month earns. If your LTV to CAC ratio is 3:1 or better, a loss this month can still be a good investment, so the card shows blue instead of red.