Growth & SaaS metrics

CAC payback period calculator

CAC payback measures how many months of gross profit it takes to recover what you spent winning a customer. It is the single best predictor of how much growth your cash balance can fund.

Inputs

Result

CAC payback

5.3 months

Customer acquisition cost
USD 800
Monthly gross profit per customer
USD 150
Expected lifespan
33.3 months
Share of lifetime spent repaying CAC
15.99%
Spend recycled per year
2.25x
  • Payback under 12 months usually means growth can be self-funded from operating cash.

How to use this calculator

  1. 1Enter sales and marketing spend for the period and customers acquired.
  2. 2Enter average revenue per customer per month and gross margin.
  3. 3Compare payback with the cash you hold to see how fast you can safely scale.

Blended vs paid CAC

Blended CAC divides all sales and marketing spend by all new customers, including organic and referral. Paid CAC isolates spend and customers from paid channels, and is always the higher, more honest number for planning ad budgets.

Include salaries, commissions, tooling and agency fees. Excluding sales wages is the most common way CAC gets understated.

Why payback drives cash

With a 6-month payback, every dollar of acquisition spend recycles twice a year. At 24 months, growth has to be funded from equity or debt, because the business cannot self-finance the gap.

Under 12 months is strong for SMB motions, 12-18 months is typical for mid-market, and beyond 24 months usually requires venture funding to sustain.

Call this tool from the API

Every calculator on this site is also an endpoint. Get a free key from the developer page and call it from your product, spreadsheet or AI agent.

curl -X POST https://utopiavalue.co/api/v1/tools/cac-payback-calculator \
  -H "Authorization: Bearer $UTOPIA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"salesMarketingSpend":120000,"newCustomers":150,"arpu":200,"grossMarginPercent":75,"monthlyChurnPercent":3,"currency":"USD"}'

Frequently asked questions

Should CAC include salaries?

Yes. Fully loaded sales and marketing payroll, commissions and tooling all belong in CAC, otherwise the payback figure flatters the channel.

How do free trials affect the number?

Count only customers who convert to paid, and count spend from the period that generated them, allowing for the trial lag.

What if payback exceeds lifetime?

The unit economics are inverted: each new customer destroys value. Fix pricing, retention or channel mix before increasing spend.