CPM vs RPM is one of the most common points of confusion in display advertising, and it is not a pedantic one. Both are quoted per thousand. Both appear in ad network dashboards. But they measure different things from different sides of the deal, and the gap between them is where publishers’ expectations tend to go wrong.
The short version: CPM tells you what an advertiser paid for ad impressions. RPM tells you what your pages earned. If you only remember one of them, remember RPM.
Are RPM and CPM the same? No: the two definitions
Google’s own definitions make the split clear. AdSense’s CPM help page puts it in one line: “CPM is the cost per 1000 impressions.” That is a cost, which means it is written from the buyer’s side. It is what an advertiser pays for a thousand views of an ad.
RPM is defined from the other side. According to Google’s AdSense help page on RPM, “Revenue per 1000 impressions (RPM) represents the estimated earnings you’d accrue for every 1000 impressions you receive.” That is revenue, written from the publisher’s side.
| CPM | RPM | |
|---|---|---|
| Stands for | Cost per 1000 impressions | Revenue per 1000 impressions |
| Whose number | The advertiser’s | The publisher’s |
| What it measures | What is paid for ad impressions | Estimated earnings per thousand page views, impressions or queries |
| Formula (AdSense) | Set by the buyer or the auction | (Estimated earnings / Number of page views) * 1000 |
| AdSense example | Not applicable | $0.15 from 25 page views gives ($0.15 / 25) × 1000 = $6.00 page RPM |
| Use it to | Understand advertiser demand | Plan and compare your own income |
How RPM is calculated
The AdSense formula is simple: “RPM = (Estimated earnings / Number of page views) * 1000”. Google’s worked example uses $0.15 earned from 25 page views, which comes out at ($0.15 / 25) × 1000, or a page RPM of $6.00.
Notice what the denominator is. Page RPM divides by page views, not by ad impressions. That one choice is why RPM is the more honest number for a publisher: it measures what a page earns, however many ads sit on it and however many of them actually load. Google also reports RPM against ad impressions and queries, so check which version a dashboard is showing before you compare figures.
Google adds a caveat that is easy to skim past: “RPM doesn’t represent how much you’ve actually earned; rather, it’s calculated by dividing your estimated earnings by the number of page views, impressions, or queries you received, then multiplying by 1000.” RPM is a rate, not a payment. It is useful for comparison, but your actual payout is a separate figure.
Why the two numbers rarely match
Two forces push RPM and CPM apart, and they pull in opposite directions. Neither needs invented numbers to understand; it is arithmetic.
Several ads per page push RPM up. CPM is priced per ad impression. A page view on a page with several ad units can generate several ad impressions. Because page RPM divides earnings by page views rather than ad impressions, a page carrying several ads can show an RPM higher than the CPM of any single ad on it.
Revenue share pushes RPM down. The advertiser’s spend does not all reach the publisher. The network takes its share before your earnings are counted, so the revenue in your RPM is smaller than the cost in the advertiser’s CPM.
Other factors widen the gap further. Not every page view loads every ad, not every ad slot is filled, and some impressions are not paid at all. All of that lowers your earnings per page view without changing what advertisers bid.
CPM is the price of an ad. RPM is the value of a page. Plan your income on the second.
CPM vs RPM: which number should publishers watch?
RPM, almost always. It answers the question you actually have: what is a thousand visits to this site worth? It folds in ad density, fill, revenue share and audience value in one figure you can compare month to month and page to page.
CPM still has a use. It tells you about advertiser demand, which helps explain why RPM moves. Some networks quote CPM-style rates, and some compare themselves on them; when you see one, translate it into what it would mean per page view before you judge it. Our ad network comparison is a better starting point than any headline rate.
How a network pays you also changes over time. AdSense is the obvious example, covered in our explainer on whether AdSense pays per click. RPM sidesteps the question: it does not care how the money was calculated, only how much there was per thousand.
To make RPM useful rather than decorative, break it down. A single site-wide figure hides the pages that carry your income and the ones that drag it down. Compare RPM by page type, by country and by device, and compare each month with the same month a year earlier rather than the one before, because advertiser demand is seasonal. When RPM drops, those splits tell you whether the cause is your traffic mix, your ad set-up or the market. A falling CPM points at the market; a falling RPM with steady CPM points at something on your side.
RPM and CPM meaning outside AdSense
The same two terms turn up across advertising, including on YouTube, where creators see both. The logic is the same: CPM sits on the advertiser’s side, RPM on the creator’s or publisher’s. If a platform shows you both, the gap between them is the platform’s cut plus everything that stops an ad from being shown or paid.
Premium ad networks are usually judged on RPM for the same reason. When publishers compare networks, they compare what each one earns per thousand sessions or page views on the same traffic. Thresholds such as the revenue gate in our post on Mediavine requirements only make sense once you think in RPM terms, because revenue is traffic multiplied by what each visit earns.
If you want to go deeper on the AdSense side, our guide to AdSense RPM covers what moves the number and where to find it in your reports. The monetization hub sets display ads against affiliate and other models.
One limitation is worth stating. RPM is an average, and averages hide a lot. A site-wide RPM blends pages, countries, devices and seasons that can earn very differently. It tells you what your traffic earned on average over a period. It cannot tell you what any one new page, audience or niche will earn, and no published RPM from another site can either.
Frequently asked questions
Is RPM and CPM the same?
No. CPM is the cost per 1000 impressions that an advertiser pays. RPM is the estimated revenue a publisher earns per 1000 page views, impressions or queries. They measure opposite sides of the same transaction.
How do you calculate RPM?
Google’s AdSense formula is (Estimated earnings / Number of page views) * 1000. Its example: $0.15 from 25 page views gives a page RPM of $6.00.
Can RPM be higher than CPM?
Yes. Page RPM is measured per page view, and a page with several ads produces several ad impressions per view. That can lift page RPM above the CPM of a single ad, though the network’s revenue share pulls the other way.
Is RPM what I actually get paid?
No. Google says RPM does not represent how much you have actually earned; it is a rate calculated from estimated earnings. Your payment is a separate figure.
The takeaway CPM is what an advertiser pays per thousand ad impressions; RPM is what you earn per thousand page views. Ad density pushes RPM up, revenue share pulls it down. Plan your income on RPM, and treat it as an estimate.
