Cost per impression (CPI) is a business efficiency measure common to advertising in
CPI can refer to cost per printed advertisement or to cost of the advertisement displayed per user on a website. In either case, CPI does not guarantee that a customer views the advertisement, but merely that it is displayed. CPI focuses on the cost per potential view.
CPI is the number of impressions divided by the cost per impression. In print, an impression is an ad printed, like in a magazine or newspaper. In web advertising, an impression is a potential view per ad successfully delivered to a browser. A single webpage might create multiple impressions for an advertiser by having multiple ads. Cost per impression, cost per click and cost per order are all part of estimating the overall profitability of online advertising.
The CPI for print advertisements can be counted on per ad in every magazine sold. Ad blockers and IP address blacklists are challenges for web advertising. However, CPI is not counted when web ads are not delivered to a webpage.