HesapHanem

CAC Payback Period Calculator

Enter CAC, monthly revenue per account, and gross margin to find the CAC payback period.

How it is calculated

First the tool finds the gross profit each account brings in per month: monthly margin = ARPA × gross margin % / 100. Then it divides the acquisition cost by that figure: payback months = CAC / monthly margin. CAC is the total cost of winning one customer (money), ARPA is average monthly revenue per account (money per month), and gross margin is a percentage between 0 and 100. Amounts are shown in US dollars and the payback is rounded to two decimals. The calculation assumes revenue and margin stay flat; it ignores churn, discounts and expansion revenue. A CAC of 0 is accepted and gives 0 months, while a margin of 0 or below, or above 100, gives no result.

Worked example

A subscription product costs $1,500 to acquire a customer, who pays $90 per month at a 75% gross margin. Monthly margin: 90 × 75 / 100 = $67.50. Payback: 1,500 / 67.50 = 22.22 months. That means the account has to stay subscribed for just over 22 months before the acquisition spend is recovered from gross profit. If the margin were 100% on the same price, payback would drop to about 16.7 months.

Try this example →

Common mistakes

  • Using revenue instead of gross profit. Dividing CAC by the full $90 gives 16.67 months, which understates payback when the gross margin is 75%.
  • Typing the margin as a fraction. Enter 75 for 75%, not 0.75, otherwise the monthly margin is a hundred times too small and the payback looks absurdly long.
  • Entering annual revenue per account in the monthly field, which makes the payback look twelve times shorter than it really is.
  • Leaving out part of the acquisition cost, such as sales salaries, tools or onboarding. A CAC that only counts ad spend makes payback look better than it is.

Sources

About this calculator

The CAC payback period tells a SaaS company how many months it takes to recover what was spent acquiring a customer, calculated as CAC ÷ (monthly revenue per account × gross margin %) — using gross-margin-adjusted revenue because that’s the portion of revenue actually available to offset acquisition spend. A shorter payback period means cash is recovered and reinvestable faster.

Startup finance and growth teams, along with SaaS investors, treat this as a core efficiency metric — a payback period under 12 months is generally considered healthy for B2B SaaS — because it shows how quickly customer acquisition spend turns into usable cash rather than sitting locked up as risk. It divides acquisition cost by the gross profit an account brings in each month, using your CAC, monthly revenue per account and gross margin, to show how many months it takes to earn the cost back.

Was this helpful?

You can pick up to 3 reactions.

Comments (1)

  • Editorial team

    Payback only means something next to how long customers actually stay. With 1200 CAC, 100 monthly revenue and an 80 percent margin the tool gives 15.00 months, while at 60 percent margin the same account needs 20.00 months. If your typical customer cancels before that point, the acquisition spend is never fully recovered, so set the result beside your own retention figures. Which margin do you use when you quote this number?

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators