Online Ad Sizes Get Fluid With Responsive Designs

Four major ad sizes are layered on top of each other to show their scale.

The most important online ad sizes include the 300 x 250, 782 x 90 and 300 x 600, but mobile sites and responsive design are driving new standards.

Two important references to current standards are available from the Internet Advertising Bureau and Google.

The IAB tries to set and maintain industry standards. Google generates billions of ad impressions from its Google Ads product for advertisers and AdSense for publishers.

The arrival of responsive design has led to different design concerns for advertisers and publishers.

For advertisers, the challenge is creating enough ad sizes to fill the growing variety of spaces on responsive sites. They also have to figure out which of the many sizes and options will work best for their businesses.

For publishers, the challenge is accommodating the many sizes that aggressive advertisers create. The more sizes they accommodate, the more money they make.

6 Important Online Ad Sizes

Until recently, the IAB had a universal package of important ad sizes that still resonates with publishers today. Google also recognizes the following sizes as important.

300 x 250

Arguably, the most important and popular size is the 300 x 250 pillow or medium rectangle ad. It appears most often in site sidebars and embedded within articles. It is an important size because it works well with advertiser graphics and also with site layouts. More and more sites are using it as a display size for their mobile editions.

728 x 90

This long horizontal strip or leaderboard appears most often at the top of site pages. As a result, it has high visibility for advertisers and site visitors who don’t scroll pages much. It has more limits with graphics, but it works well with artful text.

160 x 600

This long vertical known as a wide skyscraper is more challenging for advertisers than the above two ads because of the narrow limits on both graphics and text. Like the 300 x 250, it can work well as an embed within an article or page. It works less well in a sidebar.

300 x 600

The half page ad is a more recent arrival that solved the problem of space with a 160 x 600. It also offers much more graphical freedom and impact on site visitors. It commands better branding, greater click-through rates and usually higher CPMs.

336 x 280

If a 300 x 600 does better than a 160 x 600, a 336 x 280 large rectangle should do better than a 300 x 250, right? The answer is, yes it does. It also forces sites to use a wider sidebar, if that is where they put it, or make more room for it as an article embed.

320 x 100

The large mobile banner made its appearance after the first attempt at a mobile banner — the 320 x 50 — failed to generate enough clicks. The 320 x 100 does slightly better than the 320 x 50. But it doesn’t do as well as the 300 x 250 in a mobile design.

Secondary Online Ad Sizes

Other online ad sizes are antiquated such as the 468 x 60 — one of the original banners — and the 234 x 60 or half banner. The 120 x 600 skyscraper also is outdated after being replaced by the 160 x 600 wide skyscraper.

A few are now almost as important as the list of six above.

970 x 90

The large leaderboard makes up for the fact that a 728 x 90 at the top of the page doesn’t stretch across the entire page. It leaves large white gaps on either size. Some publishers may argue that white space is often a good thing because it makes the ad pop out more. Experimenting will tell which size is better. Some versions are expandable.

970 x 250

Like the 300 x 600, the 970 x 250 billboard has a strong branding impact because of its size. Downsides for publishers include the large amount of premium space it consumes at the top of the page. It forces viewers to scroll more to see the rest of the page’s content, which may reduce content clicks.

New IAB Standard Sizes

The Internet Advertising Bureau is moving beyond standard sizes to flexible ones because of the growth of mobile and responsive site designs.

“The new ad units are based on aspect ratio and size range and not fixed pixel sizes. Flexible sized ad units allow for ad delivery across multiple screen sizes and integration with responsive website design. The creative design can scale to different screen sizes,” IAB says.

For example, an ad with an aspect ratio of 5:1 will have that same ratio on a mobile site or desktop site. The physical size will scale according to the screen size. An ad that is 500 pixels width by 100 deep may appear 300 wide by 60 deep on mobile.