Canonical formula calculator
PAYBACK PERIOD
How long it takes to earn back what you spent acquiring a customer — the most honest test of unit economics.
What you spent on average to acquire one new customer.
Average monthly revenue from one customer, minus the cost to serve them.
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Add context for case suggestions
Optional — helps us match this calculation against relevant case studies (coming soon).
What this tells you
Payback period tells you how many months a customer needs to stay before you have recouped what you spent acquiring them. Under 12 months is healthy for most businesses. Over 18 months means your unit economics depend on customers staying longer than they typically do — a fragile place to be.
When to use it
Calculate payback whenever CAC or unit margins change. Watch the trend — payback creeping up usually means CAC is climbing, margins are compressing, or both. Both call for action before the next fundraising cycle or the next quarter of growth spend.
What it doesn’t tell you
Payback period assumes monthly contribution stays constant, which it usually does not. It also does not account for churn — a 9-month payback is meaningless if customers leave at 6 months. Always pair it with retention and LTV when making decisions.
Coming soon
Cases, plays, and benchmarks for this metric will appear here as the Moonshot knowledge libraries grow. For now: log in to track your number over time and Moonshot will surface trend warnings when the substrate fills in.