CPM, short for “cost per mille,” is a metric that we use to estimate ad revenue you can expect to receive from every 1000 pageviews. We calculate it as follows: Revenue / Pageviews * 1000 eCPM, short for “effective cost per mille,” is a metric that we use to estimate ad revenue you can expect to receive from every 1000 ad impressions. We calculate it as follows: Revenue / Ad Impressions * 1000