CAC Payback Period
Definition
The CAC payback period is the number of months it takes for a company to recover the cost of acquiring a customer through that customer's gross margin contribution. A shorter payback period means faster capital recycling and less risk, with under 12 months considered strong for SaaS businesses.
Formula
Overview
CAC payback period measures how quickly you recoup the investment made to acquire a customer. While LTV:CAC tells you the total return, payback period tells you when that return starts, and timing matters enormously for cash-constrained startups.
The formula divides CAC by the monthly gross margin per customer. Using gross margin rather than raw revenue is important because COGS must be covered before any acquisition cost can be "paid back." A payback period under 12 months is generally considered strong for SaaS; under 6 months is exceptional.
Long payback periods create a cash flow trap: you invest heavily in acquiring customers but wait months or years to recover that investment. This forces reliance on external capital to fund growth. Shortening payback, through higher prices, lower CAC, or improved onboarding that accelerates revenue, directly reduces capital requirements and improves the business's self-funding ability.
Example
CAC of $1,200, monthly ARPU of $150, and 80 % gross margin: payback = $1,200 ÷ ($150 × 0.80) = 10 months.
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