Written by Pragmi
Key takeaways
- eCPM and RPM both divide earnings by a count and multiply by 1,000; only the count differs.
- eCPM and impression RPM count ad impressions, while page RPM counts page views.
- Use page RPM to compare pages, eCPM to compare ad units, and earnings per 1,000 active users to decide whether a new format, like an offerwall, is worth adding.
What is the difference between eCPM and RPM?
eCPM and RPM both measure how much a publisher earns per 1,000 of something. The difference is what they count. eCPM (effective cost per mille) is usually earnings per 1,000 ad impressions. RPM (revenue per mille) is the name Google AdSense uses, and page RPM, the RPM most people mean, is earnings per 1,000 page views. A page with three ad units produces three impressions per view, so its page RPM is higher than its per-impression eCPM, even though the money is the same.
Both are publisher metrics. CPM without the “e” is usually what an advertiser pays per 1,000 impressions, which is a cost, not your earnings. For how these ideas apply to offerwalls, including EPC, see eCPM and EPC explained for publishers. This article focuses on the difference between the two terms.
eCPM vs RPM formulas
| Metric | Formula | What it counts |
|---|---|---|
| eCPM | earnings ÷ ad impressions × 1,000 | Each ad shown |
| Impression RPM (AdSense) | estimated earnings ÷ ad impressions × 1,000 | Each ad shown |
| Page RPM (AdSense) | estimated earnings ÷ page views × 1,000 | Each page view with ads |
| CPM | advertiser cost ÷ impressions × 1,000 | What the advertiser pays |
Google defines these terms in its own help pages. AdSense describes page RPM as estimated earnings divided by page views, multiplied by 1,000, and impression RPM as the average earnings per 1,000 impressions. It also notes that RPM does not represent what you have actually earned; it is a ratio for comparing performance. AdSense counts one page view no matter how many ads the page shows. Google AdMob, which serves apps, uses the term eCPM for the same per-impression idea: estimated earnings per 1,000 ad impressions.
A worked example
One blog article, three ad units, two numbers
A blog article gets 10,000 page views in a month. It has three ad units, but not every unit fills on every view, so it records 27,000 ad impressions. The page earns $54.
Page RPM = $54 ÷ 10,000 × 1,000 = $5.40.
eCPM, or impression RPM = $54 ÷ 27,000 × 1,000 = $2.00.
Same page, same money, two very different numbers. The dollar amounts are illustrative, not typical rates.
Now add a fourth ad unit. Impressions rise to 36,000, and earnings rise to $63 because the extra unit earns less than the others. Page RPM goes up to $6.30, but eCPM falls to $1.75. Page RPM tells you the page earns more; eCPM tells you each ad is worth less. Whether that trade is worth it depends on what the extra ad does to your readers, your bounce rate, and your search traffic.
How fill rate moves eCPM and RPM
Fill rate, the share of ad requests that actually return an ad, sits between the two metrics. Page views stay the same when an ad slot goes unfilled, but impressions drop. So a falling fill rate lowers page RPM while eCPM can stay flat, because the ads that did show still earned the same per impression. If page RPM drops and eCPM does not, look at fill rate and ad requests before you blame advertiser demand. What is fill rate? explains the formula and what moves it.
Which should you track, eCPM or RPM?
- Use page RPM to compare pages, sections, or traffic sources on a website. It answers “what is a visit to this page worth?”
- Use eCPM or impression RPM to compare ad units, ad sizes, placements, or networks. It answers “what is one ad slot worth?”
- Use earnings per 1,000 active users, or ARPDAU in apps, to compare different formats, such as display ads, rewarded video, and an offerwall. Formats that do not work per impression cannot be compared fairly on eCPM alone.
Apps rarely talk about page RPM, because there are no pages. App publishers usually look at eCPM per ad unit and revenue per daily active user. Website publishers usually lead with page RPM, because it connects directly to traffic.
eCPM and RPM for offerwalls
An offerwall does not earn per impression. It earns when a user completes an offer, sometimes days after opening the wall, and some results are later reversed. You can still calculate an eCPM per wall opening, or an RPM per page view of the page that holds the wall, and both are useful for comparing placements. But to compare an offerwall with display ads or rewarded video, earnings per 1,000 active users over a week or a month is fairer. eCPM and EPC explained walks through the offerwall numbers, and How much can you earn with an offerwall? turns them into an estimate.
Common mistakes
The most common one is comparing one network’s eCPM with another tool’s page RPM. The denominators differ, so the numbers are not comparable, and a “better” network may simply be counting differently.
The next two pull in opposite directions. Chasing eCPM alone tempts you to remove low-paying ads, which raises eCPM but can lower total earnings. Chasing page RPM alone tempts you to add ads, which works until readers leave and traffic falls. Watch both, and judge any change by total earnings over a few weeks.
- Treating CPM as your earnings. CPM is what advertisers pay; your share is lower.
- Reading one day. Both metrics swing by season, country mix, and advertiser demand. Compare weeks or months.
When display RPM stalls: adding an offerwall
If your RPM from display ads has stalled, the next gain may not come from squeezing more ads onto the page. An offerwall adds a different kind of earning: per completed action, from the users who choose to take part, and you can measure it per 1,000 active users next to your ads. The Sharklio offerwall has not launched yet, and sign-up is closed for now. When it opens, your dashboard will show earnings, clicks, conversion rate, and EPC for every period. Drop your email in the form at the end of this page and we will let you know once, on launch day. For other ways to earn, see AdSense alternatives and Offerwall vs rewarded video.
Frequently asked questions
Is RPM the same as eCPM?
They use the same formula but can count different things. Impression RPM and eCPM both count ad impressions. Page RPM counts page views, so on a page with several ads it is higher than eCPM.
Why is my page RPM higher than my eCPM?
Because each page view shows more than one ad. The same earnings divided by fewer page views gives a bigger number than when divided by more impressions.
What is the difference between CPM and RPM?
CPM is what an advertiser pays per 1,000 impressions. RPM is what you, the publisher, earn per 1,000 page views or impressions, after the network’s share.
Which is better to track, eCPM or RPM?
Track both. Page RPM shows what your traffic is worth, and eCPM shows how well each ad unit performs. To compare ads with other formats, use earnings per 1,000 active users.
How do I calculate RPM?
Divide your estimated earnings by the number of page views, or impressions for impression RPM, then multiply by 1,000. For example, $0.15 from 25 page views is a page RPM of $6.00.
