Why does Customer Acquisition Cost (CAC) matter?
It is half of the question of whether a business works at all. On its own the number means nothing — a high CAC is fine if customers are worth far more over their lifetime, and a low one is bad if they churn immediately. Its value is in the comparison: against what a customer is worth, against how long it takes to earn back, and against the same figure per channel, which is what tells you where to spend the next dollar.
What does Customer Acquisition Cost (CAC) look like in practice?
Add everything spent on winning customers in a period — ad spend, sales salaries and commission, the marketing tools — and divide by the number of new customers won in that period. Suppose a quarter's fully-loaded spend is $90,000 and it produced 60 new customers; CAC is $1,500. The instructive move is to run the same calculation per channel, because a blended number often hides one channel that is working well and another that is quietly consuming the budget.
What are the common mistakes with Customer Acquisition Cost (CAC)?
- Counting ad spend only and omitting salaries. Sales headcount is usually the largest component in B2B.
- Reporting a blended CAC across channels and losing the only insight it offers — which channel to fund next.
- Including organic and word-of-mouth customers in the denominator, which flatters the number by crediting paid acquisition with customers it did not win.
- Comparing CAC to first-month revenue rather than to lifetime value or a payback period.