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.
To calculate CPM, marketers first state the results of a media campaign (gross impressions).
The Search Engine Marketing Professionals Organization (SEMPO) defines eCPM as: 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.
Example This shows that: CPP is the cost of an advertising campaign, relative to the rating points delivered.