Page RPM and CPM both use a “per 1,000” normalization, but they do not measure the same thing. The biggest difference is the denominator.
Page RPM is publisher revenue per 1,000 pageviews. CPM usually describes cost or revenue per 1,000 ad impressions, depending on context.
Page RPM formula
Page RPM = estimated revenue / pageviews x 1,000. If a site earns $500 from 100,000 pageviews, its Page RPM is $5.
CPM formula
CPM = campaign cost / impressions x 1,000. If an advertiser spends $500 for 100,000 impressions, the CPM is $5.
Why equal numbers do not mean equal economics
One pageview can contain more than one ad impression, and not every ad slot is necessarily viewable or monetized. That means a $5 Page RPM and a $5 CPM are not interchangeable.
Which metric should you use?
Publishers planning site revenue often benefit from Page RPM because pageviews are easy to connect to content traffic. Advertisers buying reach frequently use CPM. For performance campaigns, CPC, CPA and ROAS can be more decision-useful.
Calculate both metrics
Use the Page RPM Calculator for publisher revenue and the CPM Calculator for impression cost.
