Digital web publishers frequently confuse impression eCPM with total Page RPM. Understanding the mathematical relationship between ad density, viewability, and effective earnings is critical to monetization growth:
1. The Universal Page RPM Formulation
Page RPM ($) = ( Estimated Total Earnings ÷ Total Pageviews ) × 1,000
Page RPM is the ultimate bottom-line monetization metric because it reflects the gross revenue each 1,000 visitors generate, regardless of how many ad units are rendered on screen.
2. Impression eCPM vs Ad Density Multiplier
Effective Page RPM = Base_Niche_RPM × Geo_Multiplier × [ 1 + (Units - 1) × 0.25 ] × ( CTR ÷ 1.5 )
Adding a second ad unit does not double your revenue because subsequent impressions compete for lower advertiser bids and reduce overall page viewability. A balanced placement of 3 ad units provides optimal revenue without degrading Core Web Vitals.