cost per acquisition

Cost Per Acquisition

The cost to achieve a specific, defined marketing outcome — a purchase, lead, sign-up, or download. Formula: total spend ÷ number of acquisitions in the period. Often used interchangeably with CAC but distinct: CPA is typically channel-specific and action-specific, while CAC is company-wide and customer-specific.

When you'd see it: Digital ad campaigns where the goal is a specific action: 'Our Google Ads CPA for demo requests is $150, and our LinkedIn CPA is $420.' Platforms like Google Ads offer Target CPA bidding, where you set a desired CPA and the algorithm adjusts bids to hit it. Also common in performance marketing agency reporting.

Why it matters: CPA tells you what each marketing action costs per channel, making it possible to compare efficiency across campaigns and optimize budget allocation. Set a target CPA based on the value of the conversion action (average deal size × close rate, or LTV of acquired customers) and manage campaigns to stay below it. CPA above target = losing money on acquisition.

Common mistakes: Conflating CPA with CAC. CPA is a channel-level metric for a specific action; CAC is a company-wide blended cost for a full customer. A $50 CPA for a lead is only useful if you know the lead-to-customer rate and the revenue per customer. Also: optimizing to CPA for a conversion that doesn't represent real buying intent — a low CPA for whitepaper downloads is meaningless if downloads don't convert.

Related CAC, ROAS, CPC, conversion rate, MQL