CPA measures the cost of acquiring a defined conversion event. Learn how CPA relates to CAC in a marketing KPI tree.
Cost Per Acquisition (CPA) is Spend ÷ Conversions, where 'conversion' is a defined event (lead, signup, install, purchase). CPA is channel- and event-specific, while CAC is the blended cost across all channels for a new paying customer. In a KPI tree, channel-level CPAs roll up into blended CAC, and the gap between them exposes funnel efficiency between the initial conversion event and a paid customer.