SaaS & growth

CAC Payback Period Calculator

Estimate how many months of customer contribution recover acquisition cost.

Free, no sign-upRuns in your browserReviewed October 2026Formula & methodology
US dollars
US dollars
US dollars

Results update as you type. Your numbers stay in this browser.

Acquisition paybackExample10 monthsmonths
Monthly contribution
$30.00
Annual contribution
$360.00

Understand the result

What is CAC Payback Period?

CAC payback period is how many months it takes a new customer’s monthly contribution to repay what it cost to acquire them. Divide CAC by monthly revenue minus monthly cost to serve: a $300 CAC and $30 of monthly contribution pay back in 10 months.

Payback monthsCAC ÷ (Monthly revenue − Monthly cost to serve)
With gross marginCAC ÷ (Monthly revenue × Gross margin)
Customers needed to stayAverage lifetime > Payback months

Example: a scheduling app

  1. It costs $300 in sales and marketing to win a customer
  2. The customer pays $50 a month; hosting and support cost $20
  3. Monthly contribution: $30; payback: $300 ÷ $30 = 10 months
  4. With 5% monthly churn the average customer stays 20 months, so the business earns back CAC about twice

Common mistakes

  • Using revenue instead of contribution. Payback on revenue looks faster than the cash reality.
  • Ignoring churn. A 10-month payback is risky if many customers leave before month 10.
Common questions

CAC Payback Period FAQ

What is a good CAC payback period?

Shorter is safer because cash returns sooner. Many subscription businesses aim for about a year or less, but the right target depends on how much cash you can tie up in growth.

How does churn affect payback?

If customers leave before the payback month, you never recover their acquisition cost. Compare payback with average customer lifetime (1 ÷ monthly churn).

Should annual prepayments change the calculation?

Annual upfront billing returns cash immediately, so cash payback can be zero months even if the economic payback is longer. Track both.

Guides for this calculation

Build context around the numbers with worked examples from our guides.

CAC Payback Period: Calculate Months to Recover Acquisition Cost →