What is CAC?
Also known as
Customer acquisition cost
CAC (customer acquisition cost) is what you spend to win one new customer: acquisition cost for a period divided by the new customers that period produced. It’s the denominator of nearly every growth-efficiency argument, and it’s meaningless until you state which costs and which customers went into it.
Blended vs. paid CAC
Blended CAC divides all sales and marketing cost — ad spend, salaries, tooling, content, events — by all new customers, including the ones who found you organically. It’s the honest company-level number, the one that tells you whether growth is affordable overall.
Paid CAC divides paid media spend by the customers attributable to paid channels only. It’s the number you use to decide whether to spend more on a specific channel.
Blended CAC is always lower than paid CAC when organic works, and the gap between them is a rough measure of how much your brand and content are doing for free. Problems start when the two get quoted interchangeably: a team reports flattering blended CAC to the board while making budget decisions on channels that, measured properly, don’t pay back. Label every CAC number with its scope.
CAC payback
CAC payback is how many months of gross profit from a new customer it takes to recover their acquisition cost — CAC divided by monthly gross-margin-adjusted revenue per customer. It’s usually more actionable than CAC alone because it’s a cash question: how long until this customer stops being a hole in the bank account? Twelve months or less is comfortable for most subscription businesses; long payback works only if you can fund it.
LTV:CAC
The other standard framing compares LTV to CAC. The rule of thumb is a ratio of 3:1 or better, but treat it gently. LTV depends on an assumed lifetime derived from churn, so a small change in the churn assumption swings the ratio dramatically, and an unusually high ratio often means you’re underinvesting in acquisition rather than winning. Use gross profit, not revenue, in LTV or the ratio is fiction.
Common traps
Use a consistent attribution window, count fully-loaded costs including salaries, and align the period so that spend and the customers it produced belong to the same window — spend in March rarely converts in March. Break CAC down by segment too: a single company-wide figure hides the fact that enterprise and self-serve customers cost wildly different amounts to win.
For the SQL, the source tables, and channel-level breakdowns, see the CAC metric guide; for the top of the same funnel, cost per lead.
Related terms
Put it to work
- CAC — Metric
- LTV — Metric
- Cost per lead — Metric
- Marketing analytics — Overview
