What is CAC payback period?
CAC payback period is the number of months it takes to recover the cost of acquiring a customer, using the gross profit that customer generates. It is a key cash-efficiency metric for SaaS.
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Definition
CAC payback period is the number of months it takes to recover the cost of acquiring a customer, using the gross profit that customer generates. It's a cash-efficiency metric: the shorter the payback, the sooner each acquisition dollar can be reinvested. It's distinct from LTV:CAC, which measures whether a customer is worth acquiring rather than how fast you get your money back.
How to calculate CAC payback period.
CAC Payback (Months) =
CAC ÷ (Monthly ARPA × Gross Margin %)
The key detail is gross margin: you recover acquisition cost out of gross profit, not revenue. A $150/mo customer at 80% margin contributes $120/mo toward payback — omitting margin makes payback look faster than it is.
CAC payback example.
As a quick benchmark: under 12 months is healthy for most B2B SaaS, and under 6 is excellent — see the full guide for benchmarks by segment and how to reduce payback.
This is the short definition.
For the full breakdown — SaaS benchmarks by go-to-market motion, the six levers that shorten payback, and common mistakes — read the complete guide:
Why it matters for attribution.
CAC payback is only meaningful per channel and tied to real paying customers — a blended number hides which channels recover cash fast and which drag. Signal Sparrow computes payback per channel from Stripe revenue in ROAS & CAC payback, or you can see how to measure it in your own numbers.
Questions, answered.
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It's how many months it takes to earn back the cost of acquiring a customer from the gross profit that customer generates — a measure of how quickly acquisition spend becomes reinvestable cash.
Divide CAC by monthly gross profit per customer: CAC ÷ (monthly ARPA × gross margin). For example, a $300 CAC with $120 monthly gross profit is a 2.5-month payback.
For most B2B SaaS, under 12 months is healthy and under 6 is excellent, though it varies by go-to-market motion. See the full guide for detailed benchmarks and ways to improve it.
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