Cost per acquisition (CPA) is a marketing metric that measures the total cost of acquiring a customer who completes a specific action, such as making a purchase, filling out a form, or clicking on an ad. CPA is a financial metric used to directly measure the revenue impact of marketing campaigns. It is different from the cost of acquiring a customer (CAC), which is a more general metric that measures the total cost of acquiring a customer over a longer period of time.

To calculate CPA, divide the total cost of a campaign by the number of customers acquired via that same campaign. The formula for CPA is: CPA = Campaign Cost / Conversions. For example, if a campaign costs $10,000 and ultimately drives 1,000 conversions, the CPA would be $10.

CPA is used in various paid marketing mediums, including PPC, display, social media, affiliate, email marketing, and content marketing. There is no universal benchmark for a "good" CPA, as every online business has different margins, prices, and operating expenses. However, businesses can determine an acceptable CPA for ecommerce acquisition by understanding their average order value (AOV) and customer lifetime value (CLV).

Knowing the cost per acquisition is essential for every business, as it helps measure the efficiency and effectiveness of marketing campaigns. By understanding and effectively managing CPA, businesses can optimize their marketing efforts and improve their revenue.