In digital advertising, cost per action (CPA) is a metric that defines how much an organization pays when a user takes a certain action. Such actions may include filling out a form, signing up for a newsletter, downloading an app, etc.


To measure CPA, advertisers usually divide the total number of acquired users by the total ad-buying spend, though there are more complex formulas.


Sometimes, the term ‘cost per acquisition’ is used interchangeably with cost per action, though the former has a narrower meaning.