Banner Templates in GIMP

• When you create a new file in GIMP -- using either "Ctrl + N" or "File" > "New" -- you can choose from a series of pre-made templates using the "Template" drop-down menu at the top of the dialog. These templates do not contain any image data, but instead use preset dimensions, orientation and resolutions. GIMP has default settings for two banners types. The "Web Banner Common" creates a 468 pixels wide and 60 pixels tall banner with 72 pixels per inch. The other option is "Web Banner Huge," which is 728 by 90 pixels. For any other sizes you'll need to set the dimensions manually.
  
  

Setting Custom Banner Sizes

• Instead of choosing a template from the drop-down menu, set the dimensions of your banner manually by setting the width in the "Width" box and the height in the "Height" box. You can set this to whatever you want, though if you're creating a banner for another website it's best to double-check their dimension specifications. 72 pixels per inch is perfectly sufficient for a web banner, as pixels per inch isn't really relevant for digital displays, but rather for printing. If you want a transparent background for your banner, click "Advanced Options" and choose "Transparency" from the "Fill With" drop-down menu. Click "OK" to create your custom banner image.
  
  

Standard Banner Sizes

• The most standard banner size is the 486 pixels wide by 60 pixels tall banner, though this is by no means the only banner type. Banners come in a variety of orientations and shapes; some are rectangle and tall, while others are completely square. Standard rectangle dimensions for banners include the 234x60 half banner, the 728x90 "leaderboard" banner, as well as the horizontal 160x600 and 120x600 "Skyscraper" banners. Smaller button-sized banners often come in 120x90, 120x60 or 88x31.
  
  

Banner File Types

• Save your banner in a way that meets the specifications for the website where you banner is being displayed, both in terms of the file type and size. If you're creating an animated banner you'll need to use the GIF format; however, GIFs made with GIMP have a limited color palette of 256 colors, and are not optimized for full images. If your banner is text-only or uses a limited color scheme, GIF may be a good choice to reduce file size. For banners with more nuance, detail and imagery you may be better off sticking with the JPG or PNG formats.