Banners are one of the most common ways to place an advertisement of one site on another website. Banners may be designed in various sizes, but staying upkeep with standard sizes make it easier for other webmasters to place your banners on their websites. The standards evolved from guidelines from several market leaders, and almost all advertisers accept or require standard banner sizes.

Besides standard banner sizes, banner file sizes are also important. Webmasters design web pages with performance in mind, and heavy graphics certainly degrade site performance. The absolute maximum banner file size should be limited to 20 KB for GIF/JPG sizes, and 30 KB for Flash images. The smaller the banner file size better off it is. The diagrams below illustrates standard banner sizes, and recommended file sizes.