As a webmaster, you likely use advertising as your primary source of income. Therefore, it is critical that before a website is ever built, you should strongly consider what sizes will make the most sense for your website.
Undoubtedly, you will have ads both above and below the fold – meaning above the bottom of an open browser window when your site’s web page first loads. You will also be able to make these placements either text or graphical display ads.
Standard ad sizes are generally guided by the Internet Advertising Bureau and even though there are many, many sizes, the most popular for web publishers and advertisers are the 728×90, 300×250 and 160×600 (or 120×600) ad units.
This isn’t to say there aren’t other well-placed sizes that earn a LOT of money. But these are the most popular ad unit sizes in use today.
Commonly referred to as a “leaderboard,” most sites have a leaderboard at the top of their interior pages if not the home page, too. With the largest screen space among the three most popular ad sizes, the leaderboard provides advertisers ample horizontal space for messaging and calls to action. Often the difficulty with these ads is the “banner blindess” inherent. Users are so used to seeing this at the top of the page that they don’t see the ad space anymore.
For Google AdSense web publishers, the 728×90 ad units will be populated by 3-234×60 text ads across the unit.
The 160×600 (or 120×600)
Known as the skyscraper or sidebar, this vertical ad unit is often used in tandem with the 728×90 to frame the content of a page. A tantalizing opportunity for advertisers working with publishers directly is the ability to “roadblock” a page and simultaneously run a graphical display ad in the leaderboard and skyscraper positions.
But for smaller websites that will just use advertising tools such as AdSense, the roadblock is less of a concern. The skyscraper also runs the risk of “banner blindness” and can hold up to 5 Google AdSense text ads.
This ad unit may not cover as much screen space, but often the 300×250 is the best for embedding into the content of pages – rather than surrounding it like the 728×90 and 160×600. Known by many names including “box” or “rectangle,” its ability to be embedded in article, for example, means that the user is likely to see the 300×250 more than the others and therefore it performs better for the advertiser. This unit is usually the highest paying on a CPM basis for display advertising exchanges and networks, but individual results can vary. Google’s AdSense can fit up to four text ads stacked vertically.
Whatever the sizes of the display ads you decide to implement, make your decisions before you ever build your website. It will save you hours of labor on an inevitable website re-design down the road.