How to calculate CAC payback period
CAC payback period is how long it takes a customer to generate enough gross profit to repay their acquisition cost. It measures capital efficiency: a fast payback frees cash to reinvest, while a long one strains growth even when LTV to CAC looks healthy.
Short answer
Calculate CAC payback period by dividing customer acquisition cost by the monthly gross-margin-adjusted recurring revenue per customer. For example, a 6,000 dollar CAC divided by 500 dollars monthly gross profit is a 12-month payback. It tells you how many months until a customer repays what it cost to acquire them.
Step by step
Calculate a fully loaded CAC
Include all sales and marketing costs divided by new customers. A skinny CAC understates payback and flatters your efficiency.
Find monthly gross profit per customer
Take monthly recurring revenue per customer and multiply by gross margin. Payback should be measured in profit, not revenue.
- Payback (months) = CAC / (monthly recurring revenue x gross margin)
- Use gross margin, not raw revenue
- Under 12 months is a common healthy target
Divide to get months
Divide CAC by monthly gross profit per customer to get the number of months to break even on acquisition.
Compare to your cash reality
A payback longer than your cash runway can afford is dangerous even with a great LTV to CAC ratio. Read them together.
Segment by channel
Compute payback per acquisition channel to find which sources return cash fastest and prioritize them.
How Ardovo helps
Ardovo computes payback per channel from live CAC and margin data, so Rook can show which acquisition sources return cash fastest and flag any channel whose payback stretches your runway, not just its LTV ratio.
Frequently asked questions
What is a good CAC payback period?
Under 12 months is a common healthy benchmark for SaaS, with best-in-class often under 6. Longer paybacks tie up cash and increase risk, even when the LTV to CAC ratio looks strong, so read both metrics together.
Why use gross margin in payback?
Because a customer repays acquisition cost with the profit they generate, not the revenue you bill. Using raw revenue understates the payback period and can make an inefficient acquisition engine look efficient.
How is payback different from LTV to CAC?
LTV to CAC measures lifetime profitability; payback measures how fast you recover the acquisition cost. A deal can be highly profitable over its life yet take two years to repay, which strains cash. You need both views.