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Glossary · Performance Advertising

CPA

Cost per action or acquisition. The advertiser pays when a defined action is completed.

What is CPA?

CPA, cost per action or cost per acquisition, is both a pricing model and a performance metric. As a pricing model, the advertiser pays only when a specific, pre-agreed event occurs, such as a purchase, lead, app install or subscription. As a metric, it is calculated by dividing total spend by the number of actions, letting teams compare efficiency across channels even when media was bought on CPM or CPC terms. CPA is central to performance marketing and affiliate programs, and related variants include CPL (cost per lead) and CPI (cost per install).

How CPA works

The action is agreed in advance, for example a purchase, registration or deposit, and tracked from the ad to the conversion.

  1. The advertiser defines the action that counts and how it will be validated.
  2. Tracking is set up, often with a pixel, SDK event or server-side postback, to record the action.
  3. Ads run and each completed action is attributed to the source that drove it.
  4. Total cost is divided by attributed actions to give the CPA, or the partner is paid a fixed amount per action.

Why it matters

It ties media cost directly to outcomes, which is why performance and affiliate campaigns are usually judged on it.

For advertisers

CPA connects spend directly to business outcomes, making it easier to set targets based on customer value.

For publishers

Selling on CPA shifts risk to the publisher or affiliate, so it suits partners confident their audience converts.

Practical example

Hypothetical example

A campaign spends 1,000 in currency and produces 50 sign-ups, so the CPA is 20.

Key considerations

  • Attribution windows and models strongly affect reported CPA, so they should be agreed before comparison.
  • A low CPA can hide poor-quality conversions; pairing it with retention or revenue metrics gives a fuller picture.
  • Optimizing only for CPA can concentrate spend on users who would have converted anyway.

Related terms

Related reading

Articles from the Vertoz blog.

More Performance Advertising terms

Frequently asked questions

How is CPA calculated?

Divide total campaign cost by the number of attributed actions in the same period.

What is the difference between CPA and ROAS?

CPA measures cost per outcome, while ROAS measures revenue generated per unit of spend.

What is target CPA bidding?

It is an automated strategy where the platform adjusts bids to achieve conversions at or near a target cost per action.