Effective CPM (eCPM) from Google

eCPM from Google Adsense (and talking about any other advertisement network) means Effective CPM and is calculated dividing the earnings by page impressions and multiplying it by 1000.

eCPM = Earnings / Page Impressions) * 1000

From a publisher’s perspective, eCPM is a useful way to compare revenue across different channels and advertising programs. It is calculated by dividing total earnings by the number of impressions, then multiplied by 1000.

For example if a publisher earned $350.00 from 90.000 impressions in a particular advertising project, the eCPM would equal $350 divided by 90000 (X 1000), or $3.89 (cost per thousand). While this term has been around for a long time in Internet advertising, Google has re-invented it, like they have done with most everything else they have tried. They have moved the (advertising) bar to a much higher notch.