Customer Acquisition Cost (CAC) is the average cost of winning one new paying customer, calculated as total sales and marketing spend in a period divided by the number of new customers won in that same period. A "fully-loaded" CAC includes salaries, commissions, tooling, and ad spend, not just ad spend alone.
What is Customer Acquisition Cost (CAC)?
Customer Acquisition Cost (CAC) is the average amount a company spends on sales and marketing to win one new paying customer. It's one of the most fundamental efficiency metrics in SaaS, since it sets the baseline every other acquisition-efficiency metric, like CAC Payback Period and LTV:CAC, is built on top of.
CAC formula
In words: CAC equals total sales and marketing spend in a period, divided by the number of new customers won in that same period.
Example
A company spends $90,000 on sales and marketing in a quarter, combining salaries, commissions, ad spend, and tooling. In that same quarter, it wins 60 new customers.
CAC = $90,000 / 60 = $1,500
It cost this company $1,500, on average, to win each new customer that quarter.
What actually goes into CAC?
The formula is simple, but what counts as "sales and marketing spend" varies a lot between companies, and this is the single biggest source of confusion when comparing CAC figures.
A fully-loaded CAC includes everything: sales and marketing salaries and commissions, advertising and paid media spend, tooling and software costs, event and conference spend, divided by new customers won. This is the more accurate, if less flattering, number.
A paid-media-only CAC counts only advertising spend, ignoring salaries and other overhead entirely. It's easier to calculate and useful for isolating one channel's raw efficiency, but it will always come out smaller than a fully-loaded CAC for the same business, sometimes dramatically so.
Neither definition is wrong, but they aren't interchangeable. A payback period or LTV:CAC ratio built on a paid-media-only CAC will look far healthier than the same calculation done properly with a fully-loaded number. Always check which definition is behind a CAC figure before comparing it to your own, or to a benchmark.
Why CAC alone isn't enough
CAC tells you how much you spent. It says nothing about whether that spend was worth it. A $3,000 CAC could be excellent or terrible, depending entirely on what that customer is worth in return.
That's why CAC is almost always paired with a second metric:
- CAC Payback Period turns CAC into a timeline: how many months of gross margin does it take to recover that $3,000?
- LTV:CAC ratio compares CAC against total lifetime value: is this customer worth several times what it cost to acquire them, or barely more?
A rising CAC isn't automatically bad news if ARPA and retention are rising with it. A falling CAC isn't automatically good news if it came from cutting spend on the channels that brought in your best, longest-retained customers. CAC is the input; payback and LTV:CAC are how you judge whether that input paid off.
How to lower CAC
- Improve funnel conversion rates. The same marketing spend converts more efficiently when more of the funnel, from visitor to trial to paid, is optimized.
- Shift channel mix. Some acquisition channels are structurally cheaper than others; referral and word-of-mouth growth typically carries a much lower CAC than paid advertising.
- Improve sales productivity. For sales-led businesses, a more efficient sales process (shorter sales cycles, better lead qualification) lowers the labor cost embedded in CAC.
- Invest in retention-driven referrals. Happy existing customers who refer new ones bring in business at a fraction of the cost of a cold acquisition channel.