Customer Acquisition Cost (CAC)

What is Customer Acquisition Cost (CAC)?

CAC equals total sales-and-marketing spend over a period divided by net new customers acquired in that period. 'Fully loaded' is the key word: it includes ad spend, content, tools, headcount, commissions, and any other cost that exists to win new customers. Distinguishing CAC from CPL matters — CPL is the cost of a lead, CAC is the cost of a paying customer, and the two can differ by 50x depending on conversion rates and ACV. CAC sits at the heart of two unit-economics tests: the CAC payback period (how many months of gross profit are needed to repay the CAC) and the LTV/CAC ratio (lifetime value divided by CAC; healthy SaaS targets 3x or higher).

Why it matters

• Defines the ceiling on what you can spend to win a customer profitably.
• Combined with LTV, decides whether the business model works at scale.
• Reveals channel-mix decisions — cheap CAC channels deserve more investment, expensive ones get rationalized.

Use cases

• CAC payback calculation. Months of gross profit per customer needed to repay acquisition spend.
• LTV/CAC ratio. The core SaaS unit-economics test; below 3x signals the model is breaking.
• Channel rationalization. Channels with CAC above target get reduced or paused.