"My RPM beats yours, so my setup is better"

"My RPM beats yours, so my setup is better"

Fair point: RPM is the metric every network puts front and center, so comparing it feels apples-to-apples.

It isn't. RPM (revenue per mille impressions) and EPMV (earnings per thousand visitors) answer different questions, and networks pick whichever flatters them.

🚩 Hidden variable: impressions per visitor. A site stuffing six ad units reports a modest RPM on a huge impression count. A clean three-unit site reports a higher RPM on fewer impressions. Same revenue, opposite-looking dashboards.

EPMV normalizes by visitor, so it's the only number that survives a density difference. If someone quotes RPM without saying ad count, the comparison is unanchored.

Not saying RPM is useless — saying it's the wrong unit to compare two different setups.