What is CAC payback period?
Of all the growth metrics, CAC payback is the one that most directly answers 'can we afford to grow?' It measures how long a new customer takes to pay back what you spent to win them.
Skip the math — the free cac payback period calculator runs this from your own figures.
Open the free calculator →The idea: time to recoup acquisition cost
CAC payback period is the number of months it takes for a customer to generate enough profit to cover the cost of acquiring them. Spend $300 to win a customer who delivers $50 of gross margin a month, and you recoup that in six months.
It's a cash and risk metric: the longer the payback, the more cash you tie up funding growth, and the longer you're exposed if the customer leaves early.
The formula
CAC payback = CAC ÷ (monthly revenue per customer × gross margin). The gross margin matters — you recoup CAC from the profit a customer brings, not their full revenue.
Example: a $300 CAC, $60 monthly revenue, and an 80% gross margin gives 300 ÷ (60 × 0.8) = 300 ÷ 48 = 6.25 months.
Why margin, not revenue
Using revenue instead of gross-margin revenue makes payback look faster than it really is, because serving the customer has a cost. Only the gross margin actually contributes to paying back acquisition spend.
A customer paying $60 a month at a 50% margin recoups CAC half as fast as one at a 100% margin — same revenue, very different payback. Always run it on margin.
What's a good CAC payback
It depends on your margins, growth rate, and how you're funded, but many subscription businesses target recouping CAC within about 12 months, and strong ones do it in under 6. Shorter is better because it frees cash to reinvest sooner.
The crucial comparison is against how long customers stay: if payback is longer than your average customer lifetime, you lose money on every customer no matter how fast you grow.
Use it to steer spending
CAC payback lets you compare channels and segments on a level field — a channel with a cheap CAC but low-margin customers may pay back slower than a pricier channel with better ones. Fund the ones that recoup fastest.
The free calculator below shows CAC payback from your own numbers, and the full tool compares it across channels so you can put money where it comes back quickest.
Questions
What's the difference between CAC payback and LTV:CAC?
They're complementary. LTV:CAC compares the total lifetime value of a customer to their acquisition cost — a measure of overall profitability. CAC payback measures how fast you get your money back — a measure of cash efficiency and risk. A business can have a healthy LTV:CAC ratio but a dangerously long payback that strains cash, so it's worth watching both.
Does CAC payback include ongoing costs?
It's measured on gross margin, which already nets out the direct cost of serving the customer (the cost of goods or service delivery). It doesn't subtract company-wide overheads like head office or R&D — those sit below gross margin. So CAC payback tells you how fast acquisition cost is recovered from unit-level profit, not from fully-loaded net profit.