The cost of a single desired outcome — commonly a sale, but the term is also used for any defined action (a signup, a download, a form fill), depending on how a campaign defines "acquisition."
Why it matters
CPA is the most direct way to evaluate whether a specific campaign or channel is efficient, because it ties spend to a real business outcome rather than to a proxy metric like clicks or impressions.
In a sentence
"We paused the display campaign once CPA rose above what the resulting customers were worth to us."
Related terms
- Often confused with: CAC (CPA is often used loosely to describe cost per any action, while CAC specifically refers to cost per paying customer — the two overlap depending on how "acquisition" is defined for a given business).
- Synonyms: Cost per conversion (when the defined action is a conversion event).