What is CAC payback

Formula

Payback (months) = CAC ÷ (monthly revenue per customer × gross margin)

Using margin, not revenue, keeps the math honest: margin is what pays for acquisition. With $250 of revenue and an 80% margin, each customer leaves $200 a month.

Hypothetical example

A subscription business spends $1,800 on marketing and sales to win each customer. The plan costs $250 a month, with an 80% gross margin, so $200 a month.

Payback is 1,800 ÷ 200 = 9 months. If the average customer cancels before month nine, the company loses money on every sale, however fast revenue grows.

Why payback matters

Every new customer consumes cash until it pays back. A company growing fast with a long payback can run out of money precisely when it sells more, because it pays for acquisition today and receives the margin over many months.

David Skok, in his piece on SaaS metrics, shows that profitability is weak when the time to recover CAC goes beyond 12 months, and stresses that this is a guideline, not a rule: there are situations where breaking it makes sense.

Payback and LTV:CAC

The two metrics complement each other. The LTV:CAC ratio shows how much a customer is worth in total relative to what they cost; payback shows how long it takes for that cost to come back. A customer can be worth five times CAC and still take two years to pay off, which weighs on cash.

Skok uses both: LTV at least three times CAC and CAC recovered within 12 months.

How to shorten payback

• Lower CAC: more efficient channels, pages that convert better, shorter sales cycles.
• Raise monthly value: pricing, higher tiers, add on sales.
• Improve gross margin.
• Offer annual plans paid upfront, which bring the cash forward.
• Reduce cancellations in the first months with good onboarding.

Payback outside SaaS

The idea applies to any business that wins customers for repeat purchases. In retail, payback can be measured in orders: how many purchases, at their margin, pay for acquiring the customer. If most customers buy only once, acquisition cost has to fit within the first order's margin.

Frequently asked questions

What is CAC payback?

The time, in months, that a customer's margin takes to repay the cost of acquiring them.

How do you calculate CAC payback?

Divide CAC by monthly margin per customer, which is monthly revenue times gross margin. A CAC of $1,800 and $200 monthly margin gives a 9 month payback.

What is a good CAC payback?

A widely cited benchmark, from David Skok, is recovering CAC within 12 months. It is a guideline, and the ideal depends on available cash and customer retention.

What is the difference between payback and LTV:CAC?

LTV:CAC shows total customer value relative to cost; payback shows how fast the cost comes back. Together they show value and speed.

Why use margin instead of revenue?

Because margin, after the cost of delivering the product, is what is left to pay for acquisition. Using revenue shortens payback on paper, not in the bank.

Related terms

• CACCAC (customer acquisition cost) is how much a business spends, on average, to win each new customer. You add...
• LTVLTV (lifetime value, also called CLV) is the value a customer generates for a business over the entire time...
• MRR and ARRMRR, short for monthly recurring revenue, is the sum of what customers pay each month for subscriptions and...
• ChurnChurn is the rate of customers who stop buying or cancel during a period, relative to those the business had...
• ROIROI (return on investment) is the percentage that shows how much an investment earned beyond what it cost...
• Average order valueAverage order value (AOV) is the average amount of each sale in a period: revenue divided by the number of...

Sources

• David Skok: SaaS Metrics 2.0 (For Entrepreneurs)

Rodrigo Fávaro

Founder of ROO3, a marketing and technology agency in São José do Rio Preto, Brazil. Builds AI products running in production (Tobia, gerar.app, Pense Mercado) and maintains the AI Benchmark, a public ranking of AI models.

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