CPM vs RPM
The 60-second version of the difference between CPM (advertiser cost) and RPM (creator revenue).
The short answer
CPM is the advertiser-side price per 1,000 ad impressions. RPM is the creator-side revenue per 1,000 video views — after YouTube's 45% cut and after counting views that didn't show an ad. Two metrics, two different sides of the same auction.
Why RPM is always lower than CPM
Two reasons stack. First, YouTube takes 45% of ad revenue, so a $10 CPM becomes $5.50 to the creator. Second, RPM is computed across all your views — not just monetized ones. If 70% of views see an ad, that $5.50 becomes ~$3.85 RPM. So a $10 CPM channel typically earns about $3–$4 RPM in practice.
Worked example
Imagine 100,000 monthly views, $10 CPM, 70% ads served. Advertiser-side gross: 100K × $10 ÷ 1,000 = $1,000 × 70% = $700. Creator share at 55%: $385. RPM = $385 ÷ 100K × 1,000 = $3.85. That's why YouTube money calculators use RPM (not CPM) as their core variable — RPM maps to your actual payout.
This page is a short explainer. A full guide with an embedded RPM/CPM converter is on the roadmap.