CAC Payback Period Calculator

CAC payback is the number of months a new customer takes to repay what it cost to acquire them. Most calculators divide CAC by monthly gross margin and stop. That figure assumes every customer stays until the cost is repaid, which is never true, and it ignores when the cash actually arrives.

Pages as fetched on 1 November 2026. Vivun’s CAC payback calculator, often linked, now redirects to another site.

Simple payback is CAC divided by monthly gross margin per customer: the formula CFI gives, and the one most calculators use. It answers how long a customer who stays takes to repay their cost.

Churn-adjusted payback answers the more useful question: how long the average customer you acquire takes, given that some leave each month. It adds up the expected margin per acquired customer month by month, with the survivors shrinking by your churn rate and growing by your expansion rate, and finds the month the total reaches CAC. If monthly margin divided by net churn, the most an average customer will ever pay, is less than CAC, the average customer never repays, and the calculator says so instead of returning a number.

Margin payback treats revenue as arriving monthly. When customers pay for a year up front, the cash arrives in month one, and cash payback can be immediate even when margin payback is a year. The calculator models a year’s price collected at the start of each subscription year from customers still subscribed, with delivery costs paid as they fall due. Cash payback is what decides how much acquisition a company can fund from its own revenue.

The company version uses totals instead of averages: sales and marketing spend for a period divided by the new recurring gross margin it produced in the next. Using the previous period’s spend allows for the delay between spending and closing. The calculator gives three versions: on net new MRR (new plus expansion minus churned), on gross new MRR (ignoring churn) and on new-customer MRR only. The net figure is the strictest and the one that says whether spending is growing the business; quote which one you used.

Payback says how long cash is tied up in each customer, so it decides how fast a company can grow on its own revenue. Shorter payback means acquisition can be reinvested sooner. CFI describes a target of under 12 months as strong, while noting the ideal varies with business model; enterprise contracts with long sales cycles usually run longer.

The sensitivity grid shows which lever matters more for your numbers: a lower CAC or a higher price. For the inputs, the CAC calculator builds a fully loaded CAC by channel, and the LTV calculator shows what the customer is worth over their lifetime.

1. Enter CACUse a fully loaded CAC per new customer, including people and tools.
2. Enter revenue and marginMonthly revenue per customer and gross margin.
3. Enter churn and expansionMonthly churn and expansion; churn 0 gives simple payback only.
4. Choose billingMonthly, or annual paid up front for the cash view.
5. Read the three figuresSimple, churn-adjusted and cash payback, and whether CAC is repaid at all.
6. Check company levelSwitch to whole company with spend and MRR movements for the period.