CPM is what an advertiser pays per 1,000 impressions. RPM is what a publisher earns per 1,000 — usually per 1,000 pageviews. Same "per 1,000" unit, opposite sides of the table: CPM is a cost to the buyer, RPM is revenue to the seller.
If you run ads, CPM is your number. If you host ads — a blog, a tool, a content site (as we do here) — RPM is yours, and the advertiser CPMs flowing through your pages are one of the inputs that determine it.
What each one actually means
CPM — cost per mille. "Mille" is Latin for a thousand, so CPM is the price of 1,000 ad impressions. It's an advertiser-side metric: how much it costs to put an ad in front of a thousand people. (For the full formula and examples, see the CPM calculator.)
RPM — revenue per mille. Same "per 1,000", but it measures revenue, not cost. For a publisher, page RPM is estimated earnings divided by pageviews, scaled to 1,000 views. It answers a publisher's core question: for every thousand visits, how much do I make?
Page RPM = (estimated earnings ÷ pageviews) × 1,000
CPM vs RPM at a glance
| CPM | RPM | |
|---|---|---|
| Stands for | Cost per mille (per 1,000) | Revenue per mille (per 1,000) |
| Whose number | The advertiser's cost | The publisher's revenue |
| Measured per | 1,000 ad impressions | 1,000 pageviews (page RPM) |
| Answers | What does it cost to be seen? | What do I earn per 1,000 visits? |
| You optimise it as | An advertiser buying reach | A publisher selling attention |
How CPM rolls up into RPM
The two aren't rivals — one feeds the other. RPM is essentially the result of the advertiser CPMs your pages earn, multiplied by how many viewable ad impressions (ads that actually loaded on-screen) each visit produces. A single pageview can generate several ad impressions (multiple units on the page), so page RPM is usually a multiple of any single ad's CPM:
Page RPM ≈ average ad CPM × viewable ad impressions per pageview
That's why two sites with identical advertiser CPMs can have very different RPMs: the one with more viewable ad units per page, better placement and higher engagement turns each visit into more revenue. Raise the CPMs you attract (audience, geography, content), the impressions per visit, or the viewability of each — and RPM climbs.
A worked example
Suppose your pages carry three ad units (three ad slots on the page), and advertisers pay an average $4 CPM per impression. If all three render and are viewed on a typical visit, each pageview earns roughly:
3 impressions × $4 ÷ 1,000 = $0.012 per pageview
Scale that to a thousand pageviews and you get a $12 page RPM. Notice the RPM ($12) is three times the advertiser CPM ($4) — because each visit produced three ad impressions. (Real numbers are lower once you account for fill rate (the share of ad slots that actually get filled), viewability, and the platform's revenue share (the cut Google or your ad network keeps); this is the clean version to show the mechanism.) Work out the CPM side of this with the calculator below.
Where eCPM fits in
You'll also see eCPM (effective cost per mille) on the publisher side, and it's easy to confuse with RPM because both express revenue per 1,000. The practical difference: eCPM is revenue per 1,000 ad impressions (per ad unit), while page RPM is revenue per 1,000 pageviews (across every unit on the page). eCPM is the impression-level view; RPM is the pageview-level one. On a page with several ad units, RPM will typically be higher than eCPM for exactly the reason above — more impressions per view. Work out your own with the eCPM calculator.
Which one should you watch?
- Buying ads? Watch CPM (and CPC) — they're your cost of reach. Read them with CTR and ROAS to know if that reach pays off.
- Selling ads (a publisher)? Watch page RPM — it's the clearest measure of how well your traffic monetises, and the number to grow without harming the experience that brought people in.
- Making videos? You're a publisher too, just with views instead of pageviews. The YouTube CPM calculator applies the same per-1,000 logic to a creator's revenue share.
Work out the CPM side of the equation here — or compare a single impression's cost with the cost per impression calculator:
CPM Calculator
Cost per 1,000 impressions — solve for any value.
Total amount spent.
Total ad impressions served.
Enter Cost and Impressions to see the result.
Frequently asked questions
- Is RPM the same as eCPM?
- They're very close. Both express revenue per 1,000, and publishers often use them interchangeably. The usual distinction: eCPM is revenue per 1,000 ad impressions (per ad unit), while page RPM is revenue per 1,000 pageviews (across all the ad units on a page). RPM is the pageview-level view; eCPM is the impression-level one.
- Is a higher RPM always better?
- For a publisher, a higher RPM means more revenue from the same traffic, so it's generally the number to grow. But RPM can rise simply because you added more ad units, which can hurt user experience and, past a point, traffic. The goal is higher RPM without degrading the pages people came for.
- What is CPM vs RPM in AdSense?
- In Google AdSense, CPM-style figures describe what advertisers pay, while 'page RPM' is your reporting metric: estimated earnings ÷ pageviews × 1,000. AdSense also shows impression RPM (eCPM). As a publisher, page RPM is the headline number you optimise.
- How do I increase my RPM?
- Improve ad viewability and placement, keep content that attracts higher-value advertisers and geographies, balance the number of ad units against user experience, and raise engagement so more of each visit is monetisable. Higher advertiser CPMs and more viewable impressions per page both push RPM up.
Key takeaways
- CPM = an advertiser's cost per 1,000 impressions; RPM = a publisher's revenue per 1,000 pageviews.
- Same "per 1,000" unit, opposite sides — cost to the buyer, revenue to the seller.
- RPM ≈ average ad CPM × viewable impressions per pageview, so page RPM usually exceeds a single ad's CPM.
- eCPM is revenue per 1,000 impressions; page RPM is per 1,000 pageviews.
- Advertisers optimise CPM; publishers optimise RPM. Use the CPM calculator for the cost side.