What Is Customer Acquisition Cost?

CAC quantifies how much a company spends to win each new customer. In a world where growth often comes at the expense of profitability, CAC is the metric that keeps spending discipline in check. Sustainable growth requires that the value of a customer over their lifetime (LTV) significantly exceeds the cost of acquiring them.

The simplest formula is: CAC = Total Sales & Marketing Expense / Number of New Customers Acquired. Some companies calculate a fully loaded CAC that includes overhead allocations, salaries, and technology costs for the sales and marketing teams.

The LTV:CAC ratio is the key efficiency metric. Best-practice SaaS companies target an LTV:CAC ratio of 3:1 or higher — meaning each customer generates three times more value than it costs to acquire them. Below 1:1, the company is destroying value with every customer acquired. Between 1:1 and 3:1, the model works but is not yet efficient.

CAC payback period measures how many months of revenue it takes to recover the acquisition cost. For SaaS businesses, a payback period under 12 months is excellent; 12-18 months is acceptable; above 18 months may indicate an unsustainable model.

FP&A teams should track CAC by channel (paid advertising, content marketing, outbound sales, referrals) to understand which acquisition methods are most efficient. Channel-level CAC analysis often reveals that some channels operate at 10x the efficiency of others.

For UK companies, CAC calculations should reflect the full cost of the sales and marketing function including employer NI, pension contributions, and benefits — these on-costs add 15-20% to headline salary figures.