1. The definitions
CPM — Cost Per Mille — is what advertisers pay YouTube per 1,000 ad impressions. It's a gross figure, before any revenue share. CPM is the number advertisers see when they set up campaigns in Google Ads.
RPM — Revenue Per Mille — is what you take home per 1,000 video views. It's net. It's already had YouTube's 45% cut removed, AND it's divided by all your views, including the ones where no ad played.
The single most confused statistic on YouTube is a creator reading their CPM and mentally converting it to income. That math is always wrong — CPM is always 30–50% higher than the number they'll actually see in their bank account.
2. The math relationship
Here's the conversion in detail:
1. Advertiser pays CPM (example: $10 per 1,000 impressions) 2. YouTube takes 45% → creator share is $5.50 per 1,000 ad impressions 3. But only ~55% of views have ads (shorter videos have no mid-rolls, some users have ad-block, some videos are demonetized) 4. So $5.50 × 0.55 ≈ $3.02 per 1,000 video views — that's your RPM
The calculator on this site does all this for you, but the mental shortcut is: RPM is roughly one-third of CPM. If someone tells you they have a $15 CPM, plan for about $5 RPM.
3. Which one should you care about?
If you're a creator planning your business, use RPM exclusively. It's the number that translates directly to dollars in your account.
If you're picking a niche to start a channel in, use CPM. CPM tells you what advertisers value, which is the upstream driver of everything else. High-CPM niches have high RPMs. Low-CPM niches never catch up no matter how much you grow.
If you're negotiating a brand sponsorship, know both. Brands anchor on CPM when pricing their media, so knowing what they pay via YouTube helps you benchmark what they should pay you directly. Typical rule: a direct creator sponsorship should cost the brand 0.5–1× what they'd pay for equivalent YouTube pre-roll reach.