The full form of eCPM is Effective Cost Per Mille.

Cost per mille (CPM), also called cost per thousand (CPT) (in Latin, French and Italian, mille means one thousand), is a commonly used measurement in advertising. It is the cost an advertiser pays for one thousand views or clicks of an advertisement. Radio, television, newspaper, magazine, out-of-home advertising, and online advertising can be purchased on the basis of exposing the ad to one thousand viewers or listeners. It is used in marketing as a benchmarking metric to calculate the relative cost of an advertising campaign or an ad message in a given medium.

The “cost per thousand advertising impressions” metric (CPM) is calculated by dividing the cost of an advertising placement by the number of impressions (expressed in thousands) that it generates. CPM is useful for comparing the relative efficiency of various advertising opportunities or media and in evaluating the overall costs of advertising campaigns.

For media without countable views, CPM reflects the cost per 1000 estimated views of the ad. This traditional form of measuring advertising cost can also be used in tandem with performance based models such as percentage of sale, or cost per acquisition (CPA).

Effective cost per mille

The Search Engine Marketing Professionals Organization (SEMPO) defines eCPM as:

A hybrid Cost-per-Click (CPC) auction calculated by multiplying the CPC times the click-through rate (CTR), and multiplying that by one thousand. (Represented by: (CPC x CTR) x 1000 = eCPM.) This monetization model is used by Google to rank site-targeted CPM ads (in the Google content network) against keyword-targeted CPC ads (Google AdWords PPC) in their hybrid auction.^[2][3]

In internet marketing, effective cost per mille is used to measure the effectiveness of a publisher’s inventory being sold (by the publisher) via a CPA, CPC, or Cost per time basis. In other words, the eCPM tells the publisher what they would have received if they sold the advertising inventory on a CPM basis (instead of a CPA, CPC, or Cost per time). This information can be used to compare revenue across channels that may have widely varying traffic—by figuring the earnings per thousand impressions.

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