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 ÷ (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.
- CAC
- $300
- Monthly ARPA
- $150
- Gross margin (80%)
- $120 gross profit
- CAC payback
- 2.5 months
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.
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.
