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CAC payback period calculator
How many months does a new customer need to pay back what you spent to win them? Enter CAC, monthly revenue per account and gross margin; add churn and expansion for a realistic answer. Compare the result with typical ranges for your segment and drag the sliders to see which lever shortens payback the most.
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Model. Constant monthly churn and expansion, gross profit counted from the first month. Real cohorts churn faster early on, so treat the adjusted figure as a floor rather than a promise.
Everything is calculated in your browser — nothing you enter is sent anywhere.
How to use it
- Enter CACType a known CAC, or switch to “From spend” and enter sales and marketing spend and the number of customers won in the same period.
- Describe a customerAverage monthly revenue per account and gross margin. Add monthly churn and expansion if you know them.
- Pick a benchmarkChoose the segment closest to your go-to-market to see where your payback sits among typical ranges.
- Play with leversDrag the what-if sliders to compare cutting CAC, raising ARPA and reducing churn; the dashed curve shows the scenario.
CAC payback formula
CAC payback period is the number of months it takes for the gross profit from a new customer to cover the cost of acquiring that customer. It is one of the few growth metrics that connects marketing spend directly to cash: while a customer is still “paying back”, the money you spent to win them is tied up.
Example: CAC $1,200, ARPA $150 and 80% gross margin give g = $120 a month and a simple payback of 10 months.
The simple formula assumes every customer stays until CAC is recovered. That is rarely true, so the calculator also computes an adjusted payback for the average acquired customer. With monthly churn c and monthly expansion e, the gross profit of month k is g·rk−1, where r = (1 − c)(1 + e). Summing the months gives a closed form:
With 2% monthly churn and no expansion, the same customer pays back in about 11 months instead of 10. If lifetime gross profit g / (1 − r) is below CAC, the logarithm has no solution: the cohort never pays back, however long you wait. The chart shows this as a curve that flattens below the CAC line.
What is a good CAC payback period?
There is no universal number, because payback depends on how you sell and how long customers stay. The ranges below are rules of thumb that come up again and again in SaaS operator discussions and investor updates. They are typical, not normative, and they shift with the funding climate: when capital is cheap, longer paybacks are tolerated.
- Consumer and prosumer subscriptions: about 1–6 months. Low prices and high churn leave little time to recover acquisition cost.
- SMB and self-serve SaaS: about 6–12 months. Small accounts churn more, so recovering CAC within a year matters.
- Mid-market, sales-assisted: about 12–18 months. Higher CAC from sales teams, balanced by lower churn and expansion.
- Enterprise, field sales: about 18–30 months. Long contracts, low churn and strong expansion justify a long payback.
David Skok’s widely read “SaaS Metrics 2.0” suggests recovering CAC in roughly 12 months as a healthy target for many SaaS businesses; treat that as a starting point, not a rule. More useful than any benchmark is the trend: payback of recent cohorts should be stable or falling as you scale.
Payback vs LTV:CAC
LTV:CAC tells you whether a customer is profitable over their whole life; payback tells you how quickly the money comes back. Two businesses with the same 3:1 ratio can have very different paybacks, and the one with the shorter payback can reinvest faster. For lifetime value and churn conversions, use the LTV and CAC calculator.
How to shorten CAC payback
The formula has only a few inputs, so there are only a few levers. The what-if sliders let you compare them on your own numbers.
- Lower CAC. Better targeting, higher landing-page and trial conversion, fewer steps before value. A 20% cut in CAC shortens simple payback by 20%.
- Raise ARPA. Pricing and packaging, annual plans paid upfront (which collapse payback to near zero on a cash basis), add-ons.
- Reduce early churn. Churn hits payback hardest in the first months, before CAC is recovered. Customers who never reach value in onboarding leave first; see how activation translates into revenue with the activation revenue calculator.
- Grow expansion. Seats and usage-based upgrades raise the gross profit of each month. When expansion outpaces churn, revenue per cohort grows over time.
- Improve gross margin. Payback is calculated on gross profit, so infrastructure and support costs matter as much as price.
Common mistakes
- Payback on revenue instead of gross profit. Dividing CAC by ARPA makes payback look 20–40% shorter for a typical SaaS margin.
- CAC without salaries. Paid media alone understates CAC many times over for sales-led products.
- Mismatched periods. Spend from one quarter and customers from another distort CAC, especially with long sales cycles.
- Blended CAC only. Organic and referral customers hide expensive paid channels. Calculate payback per channel where you can.
To see how churn and expansion shape the whole revenue base, try the SaaS quick ratio calculator; to test whether better trial conversion pays for itself, the trial-to-paid calculator.
Sources
- Skok D. SaaS Metrics 2.0 — A Guide to Measuring and Improving What Matters. forEntrepreneurs.com — CAC, months to recover CAC, gross-margin-based payback.
- Fader P. S., Hardie B. G. S. How to Project Customer Retention. Journal of Interactive Marketing, 21(1), 2007 — why constant churn is a simplification.
- Benchmark ranges on this page are typical rules of thumb from SaaS practice, not results of a specific study.
FAQ
How do you calculate CAC payback period?
Divide customer acquisition cost by monthly gross profit per customer: CAC / (ARPA × gross margin). For example, $1,200 / ($150 × 80%) = 10 months. To account for churn, find the month when cumulative gross profit of the average acquired customer reaches CAC; the calculator does this with a closed-form formula.
What is a good CAC payback period for SaaS?
Typical ranges are about 6–12 months for SMB and self-serve SaaS, 12–18 months for mid-market and 18–30 months for enterprise, with consumer subscriptions usually under 6 months. These are rules of thumb, not standards; the trend across cohorts matters more than a single number.
Should CAC payback use revenue or gross profit?
Gross profit. Only the money left after the direct costs of serving a customer can repay acquisition. Using revenue shortens payback artificially by the share of cost of goods sold.
Why is adjusted payback longer than simple payback?
Because some customers churn before CAC is recovered. The adjusted figure averages over the whole acquired cohort, so each month contributes a little less gross profit than the month before. Expansion works in the opposite direction.
What if payback says “never”?
It means lifetime gross profit, g / (1 − r), is lower than CAC: at current churn the average customer leaves before repaying acquisition. Reduce early churn, raise ARPA or margin, or acquire more cheaply.
How do annual prepaid plans affect payback?
On a cash basis, an annual plan paid upfront recovers CAC as soon as 12 months of gross profit exceed CAC, often immediately. The calculator models monthly revenue recognition; for prepaid plans, look at cash payback separately.
What CAC should I enter: blended or paid?
Both are useful. Blended CAC includes organic customers and tells you about the business as a whole; paid CAC shows whether a specific channel pays back. Calculate payback per channel when spend is significant.
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