Maximum recommended banner file size

In a previous article we talked about banner standard sizes, one of the most important metrics in banner advertising. Now the second metric in the order of its importance is the file size or file weight. The file size is measured in bytes, often with the kilo- (thousand) or mega- (million) metric prefixes, and it represents the amount of disk space consumed by a particular file.

As with other files, banners (JPGs, GIFs, SWFs etc.) have certain file weights. These files are temporarily downloaded on the users’ computers when they open a web page, so the bigger a banner file is, the heavier and slower to download that web page will be. That made publishers introducing some restrictions regarding the file sizes of the banners they would accept. And that was the first step to introducing a set of universally accepted standards concerning the banner file sizes. There are different advertising networks, and they have different weight standards, here are some of them:

IAB: The recommended initial download maximum file size for all the standard banners is 40 kilobytes (KB), with a few exceptions:

Note that these file weights refer to the initial download. That means, a flash banner can have a total file weight of over 40 KB, but anything above 40 KB is dowloaded “in the background” meanwhile the flash ad/animation had already begun.

AdWords: The file size limit for all image ads is 150 kilobytes.

Aol Advertising: The maximum accepted file size is generally 40 KB for the standard banners, but there are some exceptions. You can read more here.

Right Media - the file size should be up to 37 kb.

If you’re building an advertising campaign and you need some ads, try BannerSnack. It’s a great online tool, and you can use it to make banner ads compatible with all major advertising platforms.


  1. Timur Alhimenkov January 27, 2009
  2. Jessica July 7, 2010

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