How much you spend to win a single paying customer. Cost per acquisition (CPA) is a marketing success metric that can be calculated for a campaign, a digital marketing channel (such as email), or across all channels and tactics. At a campaign level, the formula is: total campaign cost / conversions (paying customers) = CPA. This metric is commonly used to determine the results of display ad and affiliate marketing campaigns.
Whether you choose to do your marketing online or offline, one thing does not change. This is the concept that no single marketing strategy will be as effective as a combination of two or more marketing strategies.