customer acquisition cost

Customer Acquisition Cost

The blended, all-in cost to acquire one new paying customer across all sales and marketing channels. Formula: total sales and marketing spend in a period ÷ new customers acquired in the same period. The acronym CAC also exists as a stub entry; this entry provides full context.

When you'd see it: Investor decks, board reviews, and unit economics analyses — paired with LTV to produce the LTV:CAC ratio, the single most common efficiency benchmark for subscription and SaaS businesses. CAC is also used to evaluate channel efficiency: 'our CAC through paid search is $400, through content is $180.'

Why it matters: CAC is the cost side of the unit economics equation. If CAC exceeds the lifetime value of the customer (LTV), the business model fails at scale — you're paying more to acquire customers than they'll ever return. Tracking CAC by channel identifies the most efficient acquisition paths and guides budget allocation. CAC payback period (months to recover CAC from gross profit) is the liquidity version of the same insight.

Common mistakes: Calculating CAC too narrowly — including only ad spend but ignoring sales headcount, tooling, agency fees, and marketing overhead. A correct CAC includes all S&M costs. Also: comparing single-period CAC to multi-year LTV without discounting for time — the payback period and discount rate matter, especially in a high-interest-rate environment.

Related LTV, ROAS, cost per acquisition, MQL, runway