What is ad density, and how do you measure it?
Part of MFA avoidance
The short answer
Ad density is the share of a page's main content taken up by ads: the heights of all ads in the main content divided by that content's height. The Coalition for Better Ads flags mobile pages above 30 percent and desktop pages above 50 percent, and the ANA's MFA definition cites 30 percent or more on desktop.
Key takeaways
- Ad density is a ratio of heights: ads inside the main content divided by the height of the main content, not the screen.
- Headers, footers, navigation and related article blocks are left out of the calculation, and a sticky ad counts once.
- The Better Ads Standards set 30 percent for mobile web and 50 percent for desktop, or 30 percent on desktop when a sticky video ad is present.
- A single column phone layout puts each ad across the full width of the reading path, and the Coalition's mobile threshold is lower than its desktop one.
- High ad density moves a site to review; on its own it does not prove a site was made for advertising.
What is ad density on a web page?
Definition
- Ad density
- The proportion of a page's main content area occupied by advertising, expressed as a percentage of the main content's vertical height. Buyers also call it the ad to content ratio or ad load.
Ad density describes how much of what a reader scrolls through is advertising. It is a property of the page layout, not of any single ad. A page with one large unit can have the same density as a page with five small ones. Density also says nothing about how often ads change; that is covered in our guide to ad refresh. Density is one of the five traits the ANA, the 4A's, the WFA and ISBA listed when they defined made for advertising sites in 2023.
Two terms describe the same layout question. Ad density in the Coalition for Better Ads sense is a measured percentage of height. Ad to content ratio, as the ANA used it in the MFA definition, is the same idea expressed as a comparison with the rest of the web. Both measure layout, and both depend on what counts as content.
How do you measure ad to content ratio?
One public method is the one the Coalition for Better Ads (opens in a new tab) publishes. Sum the heights of all ads within the main content portion of the page, then divide by the total height of the main content portion. The main content excludes headers, footers and site navigation, including related article blocks. Ads below the main content are not included. On desktop, ads in the side rails beside the main content are included. All formats count, sticky ads once each, and pre-roll or mid-roll video that belongs to the page's own video content is left out.
Measuring ad density on one article page
- Pick an article, not the homepage. Use a page a visitor would land on from search or social, and load it fully, scrolling to the end so lazy loaded ads appear.
- Mark where the main content starts and ends. Start below the header and navigation, end where the article and its comments stop and the footer or related links begin.
- Measure the main content height. Browser developer tools show the height of each element in pixels; record the total for the content area.
- List every ad inside that area. Include inline units, side rail units on desktop and sticky units, counting each sticky unit's height only once.
- Divide and record. Ad heights divided by content height gives the density; record it with the date, the device and the URL.
What ad density thresholds have industry bodies published?
Several bodies have published lines. They come from different bodies, apply to different devices and serve different purposes, so a buyer should cite the one that matches the question being asked. The full list of experiences the Coalition rules out is in our explainer on the Better Ads Standards.
| Source | Device | Threshold | Purpose |
|---|---|---|---|
| Coalition for Better Ads, mobile web | Phone | More than 30 percent of the vertical height of the main content | One of the ad experiences the Better Ads Standards rule out |
| Coalition for Better Ads, desktop web | Desktop | More than 50 percent, or more than 30 percent when combined with a sticky video ad | Two desktop experiences in the current standards; side rail ads count |
| ANA, 4A's, WFA and ISBA MFA definition (September 2023) | Desktop example | Usually at least twice the internet average, for example 30 percent or more | One of five MFA characteristics, not a stand alone test |
| Google publisher policy | Any screen | More ads or paid promotional material than publisher content on a screen | Google-served ads are not allowed on such screens |
The ANA's announcement (opens in a new tab) describes a high ad to content ratio as usually at least twice the internet average, giving 30 percent or more for desktop as an example. Google's publisher policy (opens in a new tab) counts images, videos, games, article text and user generated content as publisher content, and does not count whitespace, headers, footers or links to other content on the site. That makes it a screen level test, while the Coalition's is a page level ratio.
Why does mobile ad density matter more?
On a phone the main content is one narrow column, so each ad sits directly in the reading path and fills the width of the screen. There are no side rails to absorb units. The mobile ad density standard (opens in a new tab) reflects that: it lists tested layouts at 50, 35 and 30 percent single column density, and sets the line at 30 percent, against 50 percent for a desktop page with side rails.
Sticky units weigh more on a small screen too. The Coalition describes a large sticky ad (opens in a new tab) as one that stays on a side of the page while the user scrolls and takes up more than 30 percent of the screen's real estate. Its mobile web list also includes a sticky video ad combined with a large inline unit of 300x600 or more. Because a sticky ad counts once in the density sum but stays on screen the whole time, a phone page can pass the density test and still feel crowded.
Phone review items beyond the density figure
- The first screen of the article shows some of the article itself, not only ads and a headline.
- No sticky unit takes more than about a third of the screen while scrolling.
- A sticky video unit is not paired with a tall inline unit on the same screen.
- Inline units are separated by paragraphs of the article, not stacked one after another.
- The phone figure is recorded separately from the desktop figure for the same URL.
Is high ad density alone proof of an MFA site?
No. The trade groups listed a high ad to content ratio as one of five characteristics, together with rapidly refreshing placements, a high share of paid traffic, generic content and templated design, and asked each advertiser to set its own tolerance. Legitimate publishers can run dense layouts too. A recipe site, a local news site or an independent hobby publisher may depend on display advertising alone, and long pages with many short sections can carry many units without crossing a threshold.
| Density finding | Other evidence | Reasonable reading |
|---|---|---|
| Above 30 percent on phones | Original reporting, a named staff, mostly organic visitors | Ad heavy publisher; review the layout with the seller, keep if within tolerance |
| Above 30 percent on phones | Slideshows, sponsored link units pointing to the site, templated sister sites | Consistent with the MFA pattern; send to full MFA review |
| Below the thresholds | Ads reload on a short timer, paid traffic sources visible | Density does not clear the site; review refresh and traffic |
| Varies by page | Some templates dense, others light | Measure several templates and judge the pages the plan would buy |
Our checklist for identifying MFA sites covers how to weigh layout with traffic, content and ownership signals, and the hub on MFA avoidance covers how to write tolerance into a policy.
What does a density review look like on a real plan?
Fictional example
A home baking brand in North Dakota and South Dakota
A fictional flour milling company that sells baking flour and bread mixes plans a display flight in North Dakota and South Dakota beside recipe, baking and home cooking content. The planner shortlists recipe blogs, regional food writers and a farm and ranch lifestyle site, then measures three recent recipe pages per site on a phone and on a desktop.
One recipe blog measures well above 30 percent on the phone because every step of each recipe is separated by a full width unit, while its desktop pages stay under 50 percent with side rail ads. Its recipes are original and tested, so the planner keeps it, notes the phone figure for the client and asks the seller whether a lighter mobile template is available in a deal.
A second site measures under the thresholds, but each recipe is split across a slideshow of pages and its traffic comes from sponsored link units on other sites. The planner removes it on those grounds, recording that density alone did not decide the case.
How does PlacementGraph measure ad density before a site reaches a plan?
Frequently asked questions
Do native and in-feed units count toward ad density?
In the Coalition for Better Ads method, all ad formats within the main content count, including inline and sticky ads. A sponsored unit that sits inside the article column is part of the ad total. Recommendation boxes placed after the article fall below the main content and outside the calculation, so review them separately.
Is ad density the same as the number of ads on a page?
No. Density is a ratio of heights, so it depends on ad size and article length as well as the count of units. A long feature with eight units can have lower density than a short news brief with three. Record both figures if a client asks about ad clutter.
Does lazy loading change the ad density figure?
It can hide ads from a quick measurement, because lazy loaded units only appear when the reader scrolls near them. Scroll to the end of the page and wait for every slot to fill before measuring, or the figure will understate the real density.
Should a buyer set its own ad density limit?
A buyer can, using the published thresholds as a starting point and adjusting by format and device. Write the limit into the MFA policy with the measurement method, so that two reviewers measuring the same page get the same answer, and treat a breach as a reason to review rather than an automatic exclusion.
Sources
- Ad Experience: Ad Density Higher than 30% [Mobile] (opens in a new tab)Coalition for Better Ads
- Ad Experience: Ad Density Higher than 50% [Desktop] (opens in a new tab)Coalition for Better Ads
- Ad Experience: Desktop Ad Density Higher than 30% with Sticky Video Ad (opens in a new tab)Coalition for Better Ads
- Ad Experience: Large Sticky Ads [Mobile] (opens in a new tab)Coalition for Better Ads
- Leading Trade Groups Define “Made For Advertising” Websites (opens in a new tab)ANA (Association of National Advertisers), September 26, 2023
- More ads or paid promotional material than publisher-content (opens in a new tab)Google Publisher Policies Help
Researched and written by PlacementGraph Research. Read how we research, source and update these pages. Corrections: diana@placementgraph.com.