Subscription churn calculator

Subscribers after twelve months is today's count multiplied by the retained share, which is one minus monthly churn, raised to the power of twelve. At 6 percent monthly churn, 94 percent stay each month, and after a year about 48 percent remain, so 1,000 subscribers become roughly 476. Average lifetime is one divided by the monthly churn rate: at 6 percent that is about 16.7 months. Lifetime revenue is that lifetime multiplied by the monthly price, so 16.7 months at 40 dollars is about 667 dollars. The twelve-month revenue figure adds up what each month's surviving subscribers pay, which is less than twelve times the starting base because the base shrinks every month.

The retained figure shows how fast the base decays and therefore how many new subscribers you must add each month just to stand still. If half your base is gone in a year, acquisition is running on a treadmill. Lifetime revenue is the ceiling on what you can pay to acquire a subscriber, and you need to apply your margin to it before comparing with CAC. The twelve-month revenue figure is the most useful for planning: it is what the current base will pay if you do nothing, and every month of churn reduction moves it up. Change the churn input by a single point and watch how much it moves.

For a subscription store, the repeat purchases lever is churn. A subscriber who stays one more month is exactly one more order, and the tool shows what that is worth across the base. Lowering churn by a point usually costs less than raising sign-ups by the same value, because the fixes are on the product and the flows: a better first box, a reminder before the renewal, an easy skip instead of a cancel, and a winback sequence for those who leave. Run the calculator at your current churn and again at your target, and the gap in lifetime revenue is the budget you can justify for retention work.