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CAC calculator

Customer acquisition cost (CAC) is what you spend, on average, to win one paying customer. It is calculated as total sales and marketing spend in a period divided by the new customers won in the same period. This calculator also returns CAC payback, the months of gross profit needed to earn that spend back. No signup, nothing stored.

CAC
€600
per new customer
Total spend
€27,000
sales + marketing
CAC payback
6.3
months to recover

Under 12 months payback is the healthy SaaS range: the customer covers their own acquisition cost inside a year and starts funding the next one.

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The CAC formula

CAC is what you spend on sales and marketing in a period divided by the new customers that spend won. CAC payback is CAC divided by the monthly gross profit one customer brings, so it is counted in months. The common mistake is counting only ad spend: sales salaries and tools belong in the spend too, or payback looks shorter than it is.

CAC         = (sales + marketing spend) / new customers
CAC payback = CAC / (revenue per customer x gross margin)

David Skok's SaaS metrics guide at forEntrepreneurs says many of the best SaaS businesses recover their CAC in 5 to 7 months, and that profitability is weak if the time to recover CAC runs beyond 12 months.

CAC on its own is only half the picture. A 600 euro CAC is excellent if customers pay 200 euros a month at high margin, and dangerous if they pay 30. That is why the payback period matters more for a startup: it converts CAC into the one currency you are short of, which is time. Pair this with the LTV calculator to see the full unit economics, and read the SaaS metrics that matter.

Common questions

What is the CAC formula?

CAC = (sales spend + marketing spend) / new customers acquired in the same period. If you spent 27,000 euros across sales and marketing and won 45 customers, your CAC is 600 euros.

What should be included in customer acquisition cost?

Everything spent to win customers: ad spend, content and SEO tools, sales salaries and commission, and the software those teams use. Leave out costs of serving existing customers, which belong in cost of goods sold, not CAC.

What is a good CAC payback period?

Under 12 months is the healthy SaaS benchmark. It means a customer covers the cost of acquiring them within a year in gross profit, then starts funding the next one. For an early startup, payback matters more than the LTV:CAC ratio because it is measured in cash and time you actually have.

What is the difference between CAC and CPA?

CPA (cost per acquisition) usually means cost per lead or signup, including free ones. CAC is cost per paying customer. Check what the campaign calls an acquisition before comparing CPA with the cost per paying customer.

CAC only matters against your runway

Put the payback estimate next to your cash runway before committing to more acquisition spend. Plainhub tracks current spending, recurring revenue and runway from the entries you record. Keep period-specific sales and marketing totals separately for CAC, then test another monthly cost as a draft plan.

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