The following are standard web ad sizes supported by the Internet Advertising Bureau (IAB), which is comprised of more than 460 leading media and technology companies and responsible for selling 86% of online advertising in the United States.

Rectangles and Pop-Ups

300 x 250 pixels—Medium Rectangle:

250 x 250 pixels—Square Pop-Up:

240 x 400 pixels—Vertical Rectangle:

336 x 280 pixels—Large Rectangle:

180 x 150 pixels—Rectangle:

300 x 100 pixels—3:1 Rectangle:

720 x 300 pixels—Pop-Under:

Banners and Buttons

468 x 60 pixels—Full Banner:

234 x 60 pixels—Half Banner:

88 x 31 pixels—Micro Bar:

120 x 90 pixels—Button 1:

120 x 60 pixels—Button 2:

120 x 240 pixels—Vertical Banner:

125 x 125 pixels—Square Button:

728 x 90 pixels—Leaderboard:

Skyscrapers

160 x 600 pixels—Wide Skyscraper:

120 x 600 pixels—Skyscraper:

300 x 600 pixels—Half Page Ad: