CAC Payback Period Calculator
Find how many months of gross profit it takes to earn back the cost of acquiring a customer — the SaaS cash-efficiency metric that sits alongside LTV/CAC.
How it works
Monthly gross profit = ARPU × gross margin · CAC payback (months) = CAC ÷ monthly gross profit
Payback period measures cash recovery, not lifetime value: how many months of gross profit it takes just to break even on the money you spent to win a customer. Because it uses gross margin rather than raw revenue, it reflects the cash actually available to fund the next sale. Best-in-class SaaS recovers CAC in under a year; anything past 18 months means growth is bottlenecked by the working capital each new customer consumes.
Worked example
A $900 CAC with $120 ARPU at 75% gross margin earns $90 of gross profit a month, so payback is 900 ÷ 90 = 10 months. On revenue alone it would look like 7.5 months, which flatters the real cash position.
Frequently asked questions
Should payback use revenue or gross profit?
Gross profit is the honest version. Revenue-based payback ignores the cost of serving the customer and understates how long your cash is tied up, so investors expect the margin-adjusted number.
What is a good CAC payback period?
Under 12 months is strong, 12–18 months is workable, and beyond 18 months usually signals inefficient acquisition or weak pricing. Shorter payback lets you reinvest cash into growth sooner.
How is payback different from LTV/CAC?
LTV/CAC asks whether a customer is profitable over their whole life; payback asks how fast you get your money back. A deal can have a great LTV/CAC ratio yet a painful payback if most value arrives years later.
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Educational estimate, not financial advice.