Cost Per Acquisition, or CPA, is the amount an advertiser pays for each completed action whether that’s a purchase, a sign-up, or a lead form submission. It’s calculated by dividing your total ad spend by the number of conversions generated.
CPA = Total Ad Spend รท Number of Conversions
Unlike CPM or CPC, CPA ties your spending directly to real business outcomes, making it one of the clearest indicators of campaign profitability. The lower your CPA relative to your product margin, the more room you have to scale. It’s a go-to metric for performance marketers who need to know exactly what each customer is costing them.