CAC payback calculator
See how many months it takes to earn back what you spend acquiring a customer — using your real CAC, revenue per customer, and margin.
Enter your customer acquisition cost, your average monthly revenue per customer, and your gross margin. The calculator works out how long it takes for that customer's margin contribution to cover what you spent acquiring them.
CAC payback calculator inputs and results
How this calculator works
Customer acquisition cost is a one-off expense, but the margin a customer generates arrives gradually, month by month. Dividing CAC by monthly margin per customer tells you how many of those months it takes before the running total of margin earned catches up to what was spent acquiring them. Before that point, the customer is a net cash cost; after it, they're a net cash gain.
This figure says nothing about churn — a customer could churn before reaching payback, in which case the acquisition cost is never fully recovered. Pairing this with your churn rate and the LTV calculator gives a fuller picture of whether your acquisition spend is actually working.
About this tool
This tool is a free calculator. Inputs: customer acquisition cost (CAC), average revenue per customer (ARPU) per month, gross margin %. Output: CAC payback period in months, and a benchmark comparison against commonly cited healthy ranges. Formula basis: CAC divided by monthly margin per customer (ARPU multiplied by gross margin).
Frequently asked questions
How is CAC payback period calculated?
Customer acquisition cost is divided by the monthly margin you earn from an average customer — average revenue per customer multiplied by gross margin. The result is the number of months it takes for that customer's margin contribution to equal what you spent acquiring them.
What's a good CAC payback period for SaaS?
A commonly cited benchmark for B2B SaaS is 12 months or less, with best-in-class companies often under 6. Longer payback periods aren't necessarily fatal, but they mean more cash is tied up before a customer becomes profitable, which matters more the faster you're trying to grow.
Why use gross margin instead of revenue in this calculation?
Revenue overstates what you actually recover from a customer, since hosting, support, and processing costs reduce it. Gross margin gives a more honest measure of how much of each customer's payment actually goes toward recouping acquisition cost.
How does this relate to customer lifetime value?
Payback period tells you how long until a customer stops being a cash cost and starts being a cash gain. LTV tells you what they're worth in total over their full lifetime. A short payback period with a low LTV can still be a weak business — use the LTV calculator alongside this one to see both sides.