CPA (Cost per Action)

CPA (cost per action, or cost per acquisition) is the ad spend for each desired action, such as an order, a lead or an app install. CPA = Ad spend / Number of actions (conversions).

What is CPA in marketing?

In Google Ads, the metric is called Cost / conv. (cost per conversion): total cost divided by the number in the Conversions column. It only counts eligible interactions such as ad clicks or video views; clicks that cannot be tracked for conversions are removed from the calculation (Google Ads Help, Understand your conversion tracking data, accessed November 2026).

On Meta, the equivalent is Cost per result = amount spent / results, where a “result” is the objective you set for the campaign. When data is partial or missing, Meta may use statistical modeling to account for some results (Meta Business Help Center, Cost per result, accessed November 2026).

CPA is also a way of buying media: you pay only when an action happens, common in affiliate marketing.

CPA formula

CPA = Ad spend / Conversions

Spend VND 20 million, get 80 leads, and CPA is VND 250,000. You can also derive CPA from CPC: CPA = CPC / Conversion rate. A CPC of VND 5,000 at a 2% conversion rate gives a CPA of VND 250,000. To lower CPA, cut CPC or raise the conversion rate.

Target CPA in Google Ads

Target CPA is an automated bid strategy: you set the average cost per conversion you want, and Google Ads sets bids based on how likely each auction is to convert. Some conversions cost more than the target and some less, but on average Google tries to keep cost per conversion at the target. Key points (Google Ads Help, About Target CPA bidding, accessed November 2026):

• Conversion tracking must be set up first.
• A target set too low can make you miss clicks that would have converted, so total conversions drop.
• The recommended target is your average CPA over the last 30 days, adjusted for conversion delays. Google suggests evaluating over 30 days with at least 30 conversions.
• Daily spend can reach up to 2 times your average daily budget, within the monthly charging limit.
• From June 2026, “Maximize conversions with a Target CPA” is relabeled “Target CPA”; bidding behavior does not change.

What CPA is acceptable?

Your maximum CPA is what one conversion is worth to you. Ecommerce: an order of VND 500,000 at a 40% gross margin leaves VND 200,000; a CPA above that loses money on the first order. Leads: with a 10% close rate and VND 5 million profit per contract, each lead is worth VND 500,000, which is your lead CPA ceiling (hypothetical example).

If customers buy repeatedly, you can accept a higher first-order CPA, as long as you calculate on lifetime value.

CPA vs. CPC vs. CAC

Frequently asked questions

Is a low CPA always good?

Not necessarily. Cheap leads with wrong phone numbers or nobody answering mean the real CPA is much higher. Calculate CPA per qualified lead or per contract, and watch for signs of lead fraud.

Is cost per action different from cost per acquisition?

In ad reporting the two names are used almost interchangeably. Acquisition tends to be used when the action wins a customer, like a purchase or sign-up; action is broader and includes installs or add-to-carts.

If you want to set target CPA on qualified leads rather than raw form fills, see Adtek’s Lead Generation page.