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CAC Payback Period Calculator
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CAC payback period is the number of months it takes for the gross margin generated by a customer to repay what it cost to acquire them: CAC ÷ (monthly revenue per customer × gross margin %). Under 12 months is the common healthy benchmark for SaaS, 5–7 months is considered excellent, and anything over 18 months puts real strain on cash flow even when the LTV:CAC ratio looks fine. This calculator returns your payback period instantly from three inputs.
Your CAC payback period
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How CAC payback period is calculated
CAC payback period = CAC ÷ (monthly revenue per customer × gross margin). If a customer costs $500 to acquire, pays $100/month, and gross margin is 80%, monthly gross profit per customer is $80, so payback is 500 ÷ 80 = 6.25 months.
Payback period answers a different question than LTV:CAC ratio: LTV:CAC tells you if a customer is profitable over their full lifetime, payback tells you how long your cash is tied up before that customer starts contributing net-new profit. A business can have a healthy 3:1 LTV:CAC ratio and still run out of cash if payback stretches past what the balance sheet can fund.
What counts as a good CAC payback period
Under 12 months is the widely used SaaS benchmark for healthy capital efficiency. 5–7 months is considered excellent and typical of the most capital-efficient public SaaS companies. Past 18 months, payback starts to constrain how fast a business can reinvest acquisition spend into more growth, even if unit economics look fine on paper.
Payback period compresses as gross margin improves or acquisition cost falls, and stretches as expansion revenue is excluded — net revenue retention and upsell timing both change the real number, so this calculator gives the base-case payback, not the blended one.
FAQ
Questions
What is a good CAC payback period?
Under 12 months is the common healthy benchmark for SaaS. 5–7 months is considered excellent capital efficiency; over 18 months puts meaningful strain on cash flow even with strong unit economics.
How is CAC payback period different from LTV:CAC ratio?
LTV:CAC ratio measures lifetime profitability of a customer; payback period measures how many months until acquisition spend is recovered. A business can have a healthy ratio and still face a cash-flow problem if payback is too slow.
Should I include expansion revenue in payback period?
Not in the base calculation. Include only the customer's initial plan revenue for a conservative payback number — adding expected upsell/expansion revenue understates real payback risk if that revenue doesn't materialize on schedule.
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