Glossary /
CPA
Efficiency & cost
CPA
What it costs to win one customer or conversion — and the metric most distorted by how each platform decides what counts as an acquisition.
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
CPA (Cost Per Acquisition) is total ad spend divided by the number of acquisitions it generated. If you spend $5,000 to get 100 conversions, your CPA is $50.
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What is CPA?
CPA answers the question every performance marketer is actually asked: what does one customer cost? It's the bridge between spend and outcomes, and the metric most campaigns are optimized and bid against. It matters because CPA ties directly to unit economics. If you know the lifetime value or average order value a conversion is worth, CPA tells you instantly whether a campaign is viable. It's also the cleanest efficiency metric for lead-gen and non-revenue goals where ROAS doesn't apply. The catch: "acquisition" is not a fixed concept. A platform-reported CPA depends entirely on what that platform counts as a conversion (a purchase, a lead, an install, an add-to-cart) and the attribution window it uses to claim credit. Change the definition and the CPA changes — without any change in actual performance.
CPA formula
CPA = Total Ad Spend ÷ Number of Acquisitions
Total Ad Spend is what you paid over the period. Number of Acquisitions is the count of the conversion events you defined — purchases, signups, leads, installs, whatever "acquisition" means for you. Divide spend by acquisitions to get the average cost of one.
Worked example
An acquisition campaign over a month.
Ad Spend
$10,000
Acquisitions
200
CPA
$50
$10,000 ÷ 200 = $50
“Acquisitions” here are platform-defined conversions inside that platform's attribution window — not verified new customers.
CPA formula
CPA = Total Ad Spend ÷ Number of Acquisitions
Total Ad Spend is what you paid over the period. Number of Acquisitions is the count of the conversion events you defined — purchases, signups, leads, installs, whatever "acquisition" means for you. Divide spend by acquisitions to get the average cost of one.
Worked example
An acquisition campaign over a month.
Ad Spend
$10,000
Acquisitions
200
CPA
$50
$10,000 ÷ 200 = $50
“Acquisitions” here are platform-defined conversions inside that platform's attribution window — not verified new customers.
How CPA differs across ad platforms
Google Ads
Google reports CPA as "Cost / conv." using the conversion actions you mark as primary and its attribution model (data-driven by default). Whether it counts every conversion or one-per-click, and the conversion window you set (up to 90 days), directly change the acquisition count and therefore CPA.
Meta
Meta reports "Cost per result," where "result" is whatever optimization event you chose, attributed under its 7-day-click / 1-day-view window. The 1-day-view credit inflates Meta's acquisition count relative to click-only platforms, pushing its reported CPA artificially low.
TikTok
TikTok reports cost per conversion for the event you optimize toward, under its own (typically shorter) attribution window. Because its windows and view-through rules differ from Google and Meta, the same real customer can be counted by TikTok, by Meta, by both, or by neither.
Common CPA misconceptions
Each platform's reported CPA reflects the true cost of acquiring a unique customer.
Platforms each claim credit under their own windows, so the same customer is often counted by more than one. Summed platform conversions overstate real acquisitions and understate true blended CPA.
CPA is a standardized metric, so a $50 CPA on Google equals a $50 CPA on Meta.
They can be counting different events over different windows. A $50 Meta CPA built on 1-day-view conversions isn't comparable to a $50 Google CPA on click-based purchases.
Frequently Asked Questions
What is CPA in simple terms?
CPA is the average cost to get one conversion — a sale, signup, or lead. Spend $5,000 to get 100 conversions and your CPA is $50.
How is CPA calculated?
Why does CPA differ across ad platforms?
How does Clarisights report on CPA?
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
CPA (Cost Per Acquisition) is total ad spend divided by the number of acquisitions it generated. If you spend $5,000 to get 100 conversions, your CPA is $50.
?
?
What is CPA?
CPA answers the question every performance marketer is actually asked: what does one customer cost? It's the bridge between spend and outcomes, and the metric most campaigns are optimized and bid against. It matters because CPA ties directly to unit economics. If you know the lifetime value or average order value a conversion is worth, CPA tells you instantly whether a campaign is viable. It's also the cleanest efficiency metric for lead-gen and non-revenue goals where ROAS doesn't apply. The catch: "acquisition" is not a fixed concept. A platform-reported CPA depends entirely on what that platform counts as a conversion (a purchase, a lead, an install, an add-to-cart) and the attribution window it uses to claim credit. Change the definition and the CPA changes — without any change in actual performance.
CPA formula
CPA = Total Ad Spend ÷ Number of Acquisitions
Total Ad Spend is what you paid over the period. Number of Acquisitions is the count of the conversion events you defined — purchases, signups, leads, installs, whatever "acquisition" means for you. Divide spend by acquisitions to get the average cost of one.
Worked example
An acquisition campaign over a month.
Ad Spend
$10,000
Acquisitions
200
CPA
$50
$10,000 ÷ 200 = $50
“Acquisitions” here are platform-defined conversions inside that platform's attribution window — not verified new customers.
How CPA differs across ad platforms
Google Ads
Google reports CPA as "Cost / conv." using the conversion actions you mark as primary and its attribution model (data-driven by default). Whether it counts every conversion or one-per-click, and the conversion window you set (up to 90 days), directly change the acquisition count and therefore CPA.
Meta
Meta reports "Cost per result," where "result" is whatever optimization event you chose, attributed under its 7-day-click / 1-day-view window. The 1-day-view credit inflates Meta's acquisition count relative to click-only platforms, pushing its reported CPA artificially low.
TikTok
TikTok reports cost per conversion for the event you optimize toward, under its own (typically shorter) attribution window. Because its windows and view-through rules differ from Google and Meta, the same real customer can be counted by TikTok, by Meta, by both, or by neither.
Common CPA misconceptions
Each platform's reported CPA reflects the true cost of acquiring a unique customer.
Platforms each claim credit under their own windows, so the same customer is often counted by more than one. Summed platform conversions overstate real acquisitions and understate true blended CPA.
CPA is a standardized metric, so a $50 CPA on Google equals a $50 CPA on Meta.
They can be counting different events over different windows. A $50 Meta CPA built on 1-day-view conversions isn't comparable to a $50 Google CPA on click-based purchases.
Related Terms
Frequently Asked Questions
What is CPA in simple terms?
CPA is the average cost to get one conversion — a sale, signup, or lead. Spend $5,000 to get 100 conversions and your CPA is $50.
How is CPA calculated?
Why does CPA differ across ad platforms?
How does Clarisights report on CPA?
See Viewable Impression across every channel in one report
See Viewable Impression across every channel in one report
See viewability and vCPM across every platform—display, video, programmatic— in one normalized report, instead of reconciling vendor numbers by hand.
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