Ad Revenue Glossary

Publishers throw around RPM, CPM and eCPM as if they're interchangeable. They're not. Here's what each term actually means, in plain English.

Ad Blocker Rate: The percentage of your visitors using software that blocks ads from loading at all. It's a genuine zero for those visitors, unlike a bounce, which still loads the page and its ads. Typically anywhere from 10-50% depending on your niche and how technical your audience is. It's an input on the calculator.
Ad Density: How much of your page's visible area is taken up by ads versus content. Too high, and it hurts user experience (and can violate ad network policies); too low, and you're leaving inventory, and revenue, on the table.
Ad Refresh: Reloading an ad unit with a new ad after a set interval, without the visitor navigating away, effectively selling the same slot more than once per pageview if someone sticks around. It increases revenue on engaged pages, but a refreshed impression often sells for less than the first one, and refreshing too aggressively can hurt the reader's experience.
Ad Unit: A single ad slot on your page, a specific size and position where an ad can render. More ad units generally means more potential revenue, but past a point, adding more can lower your overall CPM through oversupply, on top of hurting the page for readers. See Ad Density.
Bounce Rate: The percentage of visits with no further interaction beyond the first pageview. It doesn't mean zero ad revenue for that visit, since the page and its ads still loaded; it just means the visitor didn't stick around long enough to trigger a second interaction or an ad refresh. GA4 is deprecating this in favour of engagement rate, which can detect scrolling as an interaction. See how this factors into your numbers on the calculator.
Commission: The cut an ad network takes from the revenue your page earns, before you see it, typically somewhere between 20% and 32%, depending on the network. This is one of the biggest reasons AdSense, Ezoic, Mediavine and AdThrive can produce different take-home revenue from identical traffic. See how ad networks compare.
CPC: "Cost per click", an advertiser pays only when their ad is clicked, rather than per impression. Common for search and some native ad formats; less common for standard display inventory.
CPM: "Cost per mille" (per thousand), what an advertiser pays for 1,000 ad impressions. This is a buy-side price, not what you as a publisher necessarily take home; your ad network's commission comes out of it before you see any revenue.
CTR: "Click-through rate", the percentage of ad impressions that result in a click. Higher CTR generally means more relevant ad placement or better-targeted ads, though a very high CTR on display ads can also indicate accidental clicks from poor placement.
eCPM: "Effective CPM", your actual revenue divided by impressions, times 1,000. Unlike CPM (a rate advertisers are quoted), eCPM is calculated after the fact from what you actually earned, blending together every ad format, network and auction price on the page.
Fill Rate: The percentage of your ad requests that actually get filled with an ad. A low fill rate means empty ad slots and lost revenue, often a sign you need more demand partners or a lower price floor.
Header Bidding: A technique where multiple ad exchanges bid on your inventory simultaneously, in real time, before the page finishes loading, instead of the old "waterfall" model where networks were asked one at a time in a fixed order. Generally increases revenue by letting the highest bidder win regardless of which network they're on. See how ad networks compare on this.
Page RPM: Revenue per thousand pageviews: (total revenue / pageviews) × 1,000. This is the metric this whole site is about: it tells you how much a page earns regardless of how many ads are on it or which network serves them. See our calculator to work out your own.
Session RPM: The same formula as Page RPM, but divided by sessions instead of pageviews. Since a session can include multiple pageviews, Session RPM is usually higher than Page RPM for the same site. Make sure you know which one a number refers to before comparing sites.
Traffic Tier: A rough classification of how valuable a country's traffic is to advertisers, driven mostly by local advertiser spend and economic strength. Tier 1 (US, UK, Canada, Australia, etc.) typically commands the highest CPMs; Tier 2 and 3 traffic is usually worth considerably less per impression. See our breakdown on Page RPM by country.
Viewability: The percentage of your served ads that were actually visible to a user (industry standard: at least 50% of pixels in view for 1+ second). Advertisers increasingly only pay for viewable impressions, so a page with poor ad placement can serve plenty of ads and still earn very little.