Definition
Cost Per Acquisition (CPA) is the average amount an advertiser spends to win one completed conversion — an enrollment, purchase, or qualified lead — calculated by dividing total campaign spend by the number of conversions. It measures the cost of a result, not the cost of attention or a click.
In Plain Terms
CPC tells you what it costs to get someone through the door; CPA tells you what it costs to get someone to actually buy. A campaign can have a cheap CPC and a terrible CPA — that means the ads work and the landing page doesn’t.
How It Works
- Calculated as total spend ÷ total conversions, over a defined period
- Only meaningful once conversion tracking is set up correctly — an untracked conversion is invisible to CPA
- The number to compare against customer value: if a course enrollment is worth NPR 30,000 and CPA is NPR 4,000, the campaign is profitable regardless of how CPC looks
- Improved from two directions — cheaper clicks (ad quality, targeting) or a higher-converting destination (landing page, offer, follow-up)
Examples
- NPR 60,000 spent generating 15 enrollment inquiries gives a CPA of NPR 4,000 per inquiry
- Two campaigns with identical CPC but 2× different CPA, pointing to a landing page problem in the weaker one
- Setting a target CPA in Google Ads and letting the platform bid automatically toward it
Commonly Confused With
CPA vs CPC — CPC is the price of a click; CPA is the price of a conversion, several steps further down the funnel. One click almost never equals one conversion
CPA vs conversion rate — conversion rate is the percentage that convert; CPA is what that percentage costs in money. Conversion rate can improve while CPA gets worse if clicks get more expensive
