CPM & eCPM Calculator for Publishers
Use the first calculator to see how CPM, ad density, fill rate and viewability add up to your page RPM. Use the second to work out eCPM, impressions or revenue from your ad report.
From CPM to page RPM
eCPM from your ad report
CPM, eCPM and RPM explained
Ad reports use three similar-looking metrics. Mixing them up is the most common reason publishers misjudge their earnings.
| Metric | Meaning | Formula |
|---|---|---|
| CPM | Price per 1,000 ad impressions, usually what an advertiser bids | cost ÷ impressions × 1,000 |
| eCPM | What you actually earned per 1,000 impressions, across all ads and bids | revenue ÷ impressions × 1,000 |
| Page RPM | What you earned per 1,000 pageviews, across every ad on the page | revenue ÷ pageviews × 1,000 |
Because one pageview can show several ads, page RPM is normally several times higher than eCPM. A page with five ads and a $2.50 eCPM earns around $12.50 per 1,000 pageviews.
From CPM to RPM
The first calculator builds your page RPM from its parts:
- Ads per pageview: every ad unit that loads during an average pageview, including sticky, in-content and sidebar units, and units that refresh as the reader scrolls.
- Fill rate: the share of ad requests that are filled with a paid ad. Premium networks typically fill most of their impressions; unfilled slots earn nothing.
- Viewability: the share of impressions that are actually seen (at least half of the ad on screen for one second, under the common industry definition). If your CPM is quoted per viewable impression (vCPM), only those count.
Why more ads don't always mean more money
Doubling the ads on a page rarely doubles revenue. Extra units are usually placed lower on the page, where fewer readers see them, so viewability and CPM fall. Too many ads also slow the page and push readers away, which lowers pages per session and session RPM. Premium networks test density carefully for this reason. Use the calculator to see how much one extra, well-placed unit is worth before adding it.
What affects CPM?
- Audience location and niche. Advertisers bid most for US, UK, Canadian and Australian readers in commercial niches.
- Ad size and position. Large, visible units such as in-content rectangles and sticky footers earn more than small units far down the page.
- Demand. Header bidding lets many buyers compete for each impression, which is why managed networks usually beat AdSense on CPM.
- Time of year. CPMs rise through the fourth quarter and drop in January.
- Consent and cookies. Impressions without consent for personalised ads typically earn less.
eCPM from your ad report
The second calculator works with numbers straight from your ad dashboard. Enter revenue and impressions to get eCPM, or use a target eCPM to estimate revenue or the impressions you need. To turn impressions into pageviews, divide by your ads per pageview, then use the RPM calculator.